GEOG331

22FEB18

109-139pgs, very good for 'case studies' information. Slow to fast Creep - Earth Flow - Mud Flow - Debris Flow - Rock Avalanche - Flows: Chaotic mixing during movement (Debris flow) Slides - movement of coherent mass of material ex rock slide Falls - Material free falls through air ex:rock fall Typical rates of mass movements. Carson and Kirkby (1972) Heave Flow Slide ternary Fig 7.5 Pure Flow, Pure Slide, Pure Heave. Velocity profiles for ideal mass movements. Soil Creep -> Solifluction -> Landslide -> Mudflow Figure 13.15 rates and types of slope failure Carson and Kirkby (1972) Rate of Motion vs Types of slope failure. Bedrock vs Soils infographic in book? Unconsolidated vs materials. Types of mass movement: Creep - 1)Rock Creep - Rock units shale sandstone etc esp if dipping slowly move 2)Soil Creep - unconsolidated. May be caused by expansion from freezing, then contraction during thaws. Episodic process caused by heaving and settling rpoduced by 1 or more of geomorphic processes: Freezethaw, wetting drying, warmining cooling, plant roots, burrowing animals. a)Solifluction or gelifluction - Special type of creep occuring in areas of permafrost. Warm weather: Ground will begin to thaw from surface downward. All of frshly melted water cannot absorb or move through permafrost layer. Cause the upper layer of soil and regolith to become saturated and flow down with slightest of slopes as it slips over frozen ground underneath. b)Colluvium - Slope deposits. Smaller and unconsolidated (Alluvium being rivers). Heterogeneous consortium fo weathered materials (soil rock regolith) transported downslope by gravitational forces (mostly creep) and accumulated at the base of hillslopes. A slope deposit. Subsidence) Sinking of land above an aquifer, may occur slowly. venice, italy sinking at 2mm/yr. May occur quickly in a sinkhole. (Karstic aquifer) Fall - Falls and forms talus. Small rock fall on Coquihalla Highway, BC. TALUS: Accumulation of fragmented rock debris below a cliff or rock face as a result of mechanical weathering. (Also known as Scree) Slide and slump - 1) Landslipe a)rotational - Slide which surface of rupture is curved concavely upwards and the slide movement roughly rotational about an exis parallel to the ground surface and transverse across the slide. Slump block and scarps. Lots of scarps. Step like feature. A lot on coasts. Figure 4.34 feature rotation slide and example rotation slump (Varnes 1958) b)translational - Landslide mass moves along roughly planar surface with little rotation or backward tilting. Dorset Coast UK, translational slide w/ shallow planar surface. 2) Rockslide - Very large landslides rockslides most common tectonically and seismically active mtn belts where you have: Steep slopes; rapidly incising rovers and glacial valleys; jointed and fractured rock masses on slopes; fluctuations in ground water pressure; steeply dipping bedding planes Intermountain belt: Utah, Idaho, Whyoming, Montana. Hebgen Lake, Montana 1959. Two faults moved within 5 sec of eachother mag 6.3 and 7.5 earthquakes. Created landslide that dammed canyon and formed earthquake lake. Dropped No end of Hebgen Lake 7-8m, creating Seiche that sloshed back and forth for almost 12 hours. Seiche - Oscillating wave. Hebgen lake earthquake and landslide August 17, 1959 --IN TEXT BOOK-- Human Activity - Covered town of Frank, Alberta, Canada on April 29, 1903 w/ 33million cubic meters of rock in approx 2 min. Mtn composed of structurally weak Liemstone, shale, silstone, and coal layers that were deformed by weight of more massive limestone located above. Mining of coal at the turtle mtn base reduced the support to overlying materials. Lower slide lake was created june 23, 1925 when the Gros Ventre Landslide dammed the Gros Ventre River, near Jackson Hole, Wyoming. -Melt from heavy snowpack, several weeks of heavy rain, and earthquake tremors rocking the area. Later, Dam was breached in 1927 and subsequent debris flow killed 6 people in the town of kelly. Slides Translational Debris Slide: Vaiont Italy 1963. Reservoir built on a) sed rock layer w/ beds dipping towards reservoir. b) Fractures formed in the rocks due to the expansion after retreat of glaciers and river cutting Canyon, 3) Weak clay layers and numberous Limestone caverns. After v. heavy rains slide slumped down the fracture surfaces into the reservoir. See image with Limit of Landslide, Oct 9, 1963 Completed 1961 measuring 262m high 27m thick at base, build under mount tock, 100km n. venice italy. In oct 1963, heavy rains caused massive landslide, and shifted debris fell reservoir. Resulted in 50mil cubic metres water displaced over top of dam, large wave washed out towns downstream and killed 2600 people. Dam itself was in good condition only needed minor repairs after. Flow a) Earthflow - Portuguese Bend 1958 and following. X-section through PB showing seaward dipping reflectors, bentonic clay layers, a preexisting slide surface and waves eroding the base of the slope. An ancient earth flow site unstable but not moving. 1950s put dev on the area by beach. No sewers. Within a few years lower slope started to move. Watering and sweage disposal seeped down to bentonite layers. They expanded, lost strength and started to move. b) Debris Flow - Form of rapid mass movement of a body of granular solids, water, and air. Debris flow deposite which resulted from failure and collapse of a dam, Rocky Mountain National Park, Colorado. See Figure 4-27 types of flow (from pierson and costa, 1987) probably in text book? Meanvelocity vs Sediment concentration. Also Figure 4.36 Components of a typical debris flow observed near Mount St. Helens (From Pierson 1986) General characteristics of Debris Flows a) Usually follow pre-existing drainage ways b) Tend to build their own levees c) Move down valley ina series of Surges, temporary damming and breaching of channels (Wet concrete) d) Velocities range from 0.5 to 20m/sec e) Ability to travel long distances over low slopes f) highly erosive during passage through steep channels - very high shear stresses 1) Debris Avalanche c) Mud Flow 1) Hyper-concentrated flow - Two phase flowing mixture of water and sediment in a channel which has preoperties intermediate between fluvial flow and debris flow. Tau = roe g d S The force exerted on the bed by the flow is equal to the flow depth times the channel slope. The Thomas Fire, December 2017 - Burned over 280,000 acres and affected Ventura, Montecito, Carpinteria and SantaBarbara counteies, among others. Removed 'all living and dead vegetation that protected the soil beneath" USGS said, land quickly erodided when there was no veg to hold it in. Steep slope + Fire + Rain. d) Lahars e) Sturzstrom Rock glaciers: Characterized by large amount of embedding or overlying rock material and ice. Can be mass moving features or glacial. Bunch of tallus that flows down. May form moraines Figure 13.26 Giardino and Vitek, 1988. Process type, time, rate is applicable. Initial, transitional, end. https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwiYhZGq8bnZAhVm64MKHZkPA18QjRx6BAgAEAY&url=https%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2FB9780444633699000136&psig=AOvVaw1h5nrjYBVFyfN5M5Ztlq2i&ust=1519401368532455 https://www.sciencedirect.com/science/article/pii/B9780444633699000136 When brownwood res subdivision near Baytown was first developed in 1930s ground elev was nearly 10ft asl. 40yrs later neighborhood stood just a food and a half above sea level and was subj to freq flooding. 1983, hurricane alicia destroyed the subdivision, and the area became the - Became a nature center!

27FEB18

4) Flows a) Earthflow b) Debris flow 1)debris avalanch c)mud flows 1) hyper concentrated flows A hyperconcentrated flow is a 2 phase flowing mix of water and sediment in a channel which has properties intermediate between fluvial flow and debris flow. Mt. St. Helens chart pg130 Altitude vs channel distance from crater Nevados de huuascaran, peru, 1962 and 1970. An eq M=7.7 resulted in debris avalanche across snow covered glacial down slope at vel up to 335km/hr. Avalanch his small hill of glaciall till and was launched into air as airborn debris avalanche. From airborn debris blocks size of large houses fell on real houses for another 4km Mass then recombined into a debris flow 18 died. La Conchita, pleistocene slumps and debris flows Heavy rains led to failure at dpth triggering a slump and eq in 1995 which moved very slowly during day. No loss of life Heavy rains led to faster moving debris flow in 2005 which killed 10 people these flows typical of coastal flows near coasts of southern california. S = c + (sigma - mu)tan(phi) Marine Terrace: Important word. Active area tectonically. Some towing and waves. Coastal processes undermine and weaken things. Important to id colluvium filled hillside hollows or anticipating future debris flow paths. Colluvium - slope driven deposit Strength and safety factor. <1 means failure and a mass movement occurs. d) Lahars Debris and mudflow produced when large vol of volcanic ash and ejecta (pyroclasatics) become saturated with water. ex: Nevado del ruis strato-volcano, 5321m. Nov 13 1985 small eruption produced enormous lahar buried and destroyed town of armero in tolima county, columbia causing an estimated 25000 deaths,. This event later became known as the Amero tragedy the deadliest lahar in history. Armero was located in the ceter of photograph taken late 1985 e)Sturzstrom Mt St Helens landslide was a sturztrom. A unique, extremely rapid type of debris flow which has a greater horizontal movement when compared to its initial vertical drops - as much as 20 or 30 times the vertical distance - with air and dust used as an internal moving mechanism The blackhawk slide, california Mass movements Flows Debris flow, Elm Switzerland 1881 "A stream of very rapidly moving debris derived from distantintegration of fallen rock mass of very large size; the speed of a sturzstrom of 100km/hr, and its vol is commonly greater than a million cubic meters (1975) Why do some landslides travel so much far than others? JGR Earth Surface may Important concepts Internal causes of slope failure Five roles of water 1) Seds have high porosity when those void spaces filled with h2o the sed is much heavier and the driving mass increased 2) water is easily absorbed and attached externally to clay mins w/ major decrease in str 3) water flow through rocks can dissolve mins and bind rocks together. Removal of cement makes rock easier to move or a slope easier to collapse 4) water can physically erod loose materials creating caverns 5) pressure builds up in water trapped in the poors of seds being buried deeper and eeper. Seds can compess but water doesn't compress. Get abnormally high pore-water pressures which 'jacks up' the sed and makes it very easy to move. pg131 hazard map. ------------------------ Hillslope form and process Slope profiles "To what degree a factor is involved in slope formation rather than whether a factor is involved." Profiles dev on the surface of natural slope reflect major geomorph forces -Climate -Rock type and structure -Time Climate, rock type and structure, and time control the rate and type of erosional process. -Process Atypical arid slopes: Cliff debris slope and a desert plain b) typical humid-temperate slopes - Convext, straight, concave. See cv cf s cc image on guide a)convex upper segment, b) a cliff face, c) straight segment having constant slope angle, d) concave segment at the hillslope base. Up to nine slope components can be recognized. Slopes are considered: Weathering limited, transport limited. May have a bit of soil creep on top of the cliff. Cliff face may have some rock falls. Convex creep Cliff: Falls slides weathering Straight: Material transport, mass movements Concaved: Deposition Slope profile: Angle 0-4, process pedogenic, wash, creep Convex segment: occur on upper soil-covered slopes, result of soln, rain splash, sheet wash and soil creep Processes increase down slope causing an increasing angle down slope. Cliff face Chemical and physicl weathering phase Weathere material falls or slides Angle 45-65, processes weathering, rockfalls Slope profile Straight segment Occur where mass movement of coarse sediments and rock dominate eg rock falls, rock slides Uniform depth of removal maintains a straight slope angle 26-35 degrees. Concave Occur on lower slopes subject to deposition angle 0-4 processes alluvial deposition Ask for the extended model for these slope profile segments. Interfluve 0-1 degree Seepage slope 2-4degrees Convex creep slope Fall face (45 to greater than 65) Transportational midslope (26-35) Colluvial footslope Alluvial toeslope - Should really end here. Channel wall Channel bed Shown on page 141 Weathering limited slope Rate of soil/regolith production is lower than the rate of removal by erosion. Profile determined by local geology Common in arid and mountainous environments Physical weathering dominates. Detachment control - all materials forming hillslopes can be regarded as having a range of detachability with respect to particular hillslope processes. Fig 7.18 the detachability continuum for slope processes. (1988) Rock slopes: Generally lie towards the weathering limited end of the continuosu detachibility. Their form controlled by a: Weathering resistance (litho/structure) b) Shear str of the rock Detailed form of rock slopes depend on variations in their rock mass strength Not common in humit tropical environs Talus will accumulate if basal removal occurs at a slower rate than debris is supplied Common in arid regions Compound slopes. Sedimentary rocks gives the bestter slopes. Formed mostly on sed rocks (sandstone/shale) Scarp and Cuesta topography. Slope decline, Slope replacement, Parallel retreat. Pg 145 Slow weathering and relatively fast removal by falls and slides. Rock/Debris mantled slopes As Talus moves up the slope there is a transition between weathering-limited and transport-limiting slopes Slope replacement If material accumulates at the slope base faster than it can be removed. Rate of Weathering: Physical dominated due to low cover by sediment. Chemical is relatively weak and can be slowed by sediment cover. Compound or complex slopes. Compound or complex because the layers are tilted. Weathering limited slopes commonly found in arid regions where weathering and rock detachment rates are slow. Segmented Scarps Slick rocks, See graphic on the guide. Exposed rock slopes that lack a reoglith cover are referred to as "Slickrock" slopes Weathering products are rapidly removed form such steep slopes by water gravity or wind erosion Strong structural control

01MAR18

At least 20 dead after 7.5 mag earthquake hits Papua New Guinea Lots of leaching and uplifted but weakened as well in an earthquake.; May see serious landslide. Figure 11.30 Schematic illustration of the change in scarp form as the downdip retreat causes the caprock to become increasingly important component of the scarp face. Figure 11.35: Retreat of an arid cliff under influence of three types of caprock. Scarp is eroded by Rockfall block by block undermining and slumping according to the thickness, jointing and resistance of the caprock. Fallen rocks,blocks form a protective layer on the shales Talus flatiron sequence inrattlesnake Butte, Colorado: SR1 corresponds to the active slope. SR2 SR3 depict successive generations of relict slopes disconnected from the source scarp of the butte. Talus flatirons, like steps where resistant layers remain but weaker stuff is eroded. The talus protects the underlying debris. The debris from a more humid episode Figure 7.29 Talus flatirons developed by alternating wet (w) and dry (D) climate. Talus aprons and associated pediments develop Crystal Growth: Evap or groundwater flow bring water to the surface-accelerate weathering. Basal Groundwater Sapping Overland Flow Extreme Storms. Slope Decline Rain vegetation soils fluxian creep, leads to convex/concave Transport limited: Formed where the rate of weathering is more rapid than erosion. Slopes produced under this regime normally developed on any unconsolidated parent material regardless of environment, but typically found in humid-temperate environments. *More dependent on the type and rate of slope process. Slope decline: Faster erosion on steeper upper slopes and slower erosion + Possibly deposition on lower slopes. Transport limited slope - Rate of weathering more rapid than erosion Tend to develop on unconsilidated parent materials Typically formed in humid-temperate enviro where continuous cover of veg Shape related to process and not geology. Rate of Weathering Phyical only important where there is no sed cover. Chem increases in str with increasing cover. Figure 7.18 The detachability continuum for slope processes. (After A J Parsons (1988) Hillslope form) Figure 21.18 processes operating on concavo-convex slopes. Soil/Regolith mantled slopes Generally lie towards the transport limited end of the continuum of detachibility Mass movement processes domainte: Convex slope segments - Soil Creep - Rainsplash Erosion - Gelifluction. Concave slope segments - Slope wash, Talus Weathering limited, Transport limited Weathering limited areas on image have no soil - particles removed by erosion before soil can develop Areas w/ soil (sandy section with sage bushes) transport limited; that is, material that has weatherd is not being carried away (transported) before being integrated into the soil. Talus development. In places where sed supply Fluvial processes and landforms Sediment zones Delevation vs distance from drainage divide. Slope = 100 to 10%, Shallow flow 10 - 2%, gravel bedded rivers 2 to 0.1%, Sand-bedded rivers slode <0.1%, Depositional basing slope approaches zero. Drainage basin (Watershed): A natural geomorph unit consisting of a channel network defined by a drainage (topographic) divide Hydrosystem: A 3 dimensional system in which the longitudinal (SUpstream and downstream) lateral (channel margins), and vert surface (underground) components transfer energy, matter and biota Climate -> Hydrological processes -> Gomorphic processes -> Landform properties (eg soils, seds, channel forms, drainage density, gradients) Space: Source Zone This is the area from which water and sed are derived It is primarily a zone of sediment production - colluvial area Transport capacity > Sediment supply Transfer Zone For a stable channel, input of sediment can equal output - alluvial area Sed supply > Transport capacity Sediment Sink -Area of deposition (Delta, alluvial fan) These three subdivs of the fluvial system may appear Some variables Gelogy (Q sediment) Uplift, Rock type Climate (Q water and Q sed) Basin (Collection) Land Use (Q water Q sed) Channel (Transport) Delta (Deposition) Water on Hillslopes Overland flow is when Intercept maxes out and the water just flows over. --FIGURE 5.10 IN TEXTBOOK-- Figure 5.7 Schematic of stream channel showing major kinds of water contributions. Arrival of water from any given precipitation event is progressively delayed from runoff to interflow to groundwater flow. (Kochel 1992) Runoff Pathways. Slide from Mike Kirkby, University of Leeds, AGU capman Conference on Hillslope Hydrology, October 2001 Overland Flow Horton (1933) proposed mechanisms for runoff formation where: Rainfall intensity > Infiltration capacity -> Hortonian Overland Flow (HOF) Rainfall and infiltration rate (Cm/hr) vs Time (hr). Shows overland flow Infiltration capacity decreased w/ duration storm Runoff starts when the rainfall intensity is greater than the infiltration. Surface Storage and Detention: Volume of water that fills depressions on ground surface Doesn't become part of excess precipitation (Direct runoff) Must fill detention storage before runoff can occur Once flow is initiated, the barriers coalesce and sheetwash develops) Q=f(L,t) Depression storage on top, Depth and Velocity of overland flow increases downslope. Figure 5.12 Hypothetical slope showing overland flow. No EROSION OCCURS UNTIL THE FORCE OF OVERLAND FLOW (F) Overland Flow HOF is the main process responsible for sheer erosion and rill initiation on sloped surface Channelization rills grown and goin to form large gullies -> Tributaries -> Rivers When master rills devlelop, erosion produces new slopes directed towards master rill - Gross Grading Small headwater tributaries (1st order) are continuously eroding away headlands and expanding the basin Semi-arid produces the most sediment yield. HOF is an ideal model that is only appropriate for UN-VEGETATED (limited/scarce vegetation) desert regions where there is little subsurface flow Hillslope Erosion Rainsplash - Soil particles dislodged. Displacement of wet soil by raindrops . On slopes the splash is asmm resulting in progressive downslope displacement of wet soil during intense rain. Sheetwash - soil washed off in overland flow. Accentuated by raindrop impact, rainsplash erosion, surging of overland flow as small vegetation or soil dams brack Rilling - Small straight channels of overland flow Overland flow deepens downslope, reaching a crit depth where laminar flow cannot be maintained and turbulendce begins to develop Turbulent eddies suspend soil particles creating rills Gullying - Larger irregular channels Rainsplash erosion - Kinetic energy of raindrops dislodging soil particles. Effectiveness depends on: Rainfall intensity, Steepness of slope, Soil res to dislodgement, Amount of vegetation cover * *Recently burned areas, clear cut logging, mining, constuction sites, etc Bleeding in the Ocean in madagascard Channel Initiation - tau = gammaDtheta_c Shear stress of overland flow depends on depth of flow and gradient of the channel. Critical Length Measurable distance from watershed divide at which erosion develops (Xc) Persistent rain leadfs to shortening of the critical length and extension of rills and gullies Any of the rain that the soil annot absorb quickly begins to run off. The resultant flow picks up speed and power as it moves downslope, As the speed and volume of runoff increases, rills begin to dev along the slope -> OVer time the rills begin to interconnect to form larger features called Gullies -> As the gullies continue Culvert Erosion - Improper culvert design can lead to the formation and headwater extension of gullies. Soil and land - soil erosion. Revised universal soil loss equation (RUSLE) Annual soil loss (kg/ha/yr) = RxKxLSxCxP

04APR18

Change in velocity with height: Vz = 5.75 * V_* * log(z/k) Where Vz is wind velocity for given height z, V_* is a parameter called drag velocity, and k is a constant relating to surface Critical friction velocity V_*_t - A & * (rhos - rhoa / rhoa * g * D)^(1/2) D = particle diameter Backslope - Creset - Slip face Erosion happens on backslope with deposition on slip face. 3 main types Transverse, parabolic, and linear. Defined by slip face type. Vegetation reason why get parabolic rather than buchan

10APR18

Calculating Sediment Transport U*t = A[gd(rhos-rho)/rho]^(0.5) Critical Shear Velocity = Threshhold of Motion! U*t almost entirely dependent upon Grain Size d = grain diameter rho_s = density of grain How do sand grains move? Lift component (Fl), Gravity (F_G), Drag component (F_D) Entrainment threshhold as drag and lift up there is a critical value of shear velocity U_*T when grain movement is initiated. A = 0.1 highly sorted round sand, A=2.8 poorly sorted. U_*t = Asqrt((rhop-rhoa)/rhoa) * gD Dynamic entrainment Impact of saltating grains lowers threshold to move stationary grains A = 0.08 dynamic entrainment Combination of saltation and reptating grains Saltating grains rebound 50-60% Fluid threshhold applies to wind moving over a surface when no particles are in motion. Once sand movement has begun -... the impact of grains colliding with the surface puts other grains into motion. Less... CONTROLS ON THRESHHOLD Grainsize - Fine sed more difficult to entrain due to electrostatic cohesion and an aerodynamically smooth surface Bed slope - Threshhold increases upslope and decreases downslope Moisture content - Capillary forces increase cohesion Bonding agents - particle bound by silt/clay, organics, and salts Surface Roughness - Resence of vegetation, lag deposits and other non-erodible roughness elements Four methods Aeolian sed transport Suspension Saltation Reptation Creep But modified saltation is really called REPTATION, replace in book. Suspension: Only the finest particles are transported by turbulent air May last for days at high altitudes. Saltation: Leaping bouncing hopping over surface. Powers other methods of transport (ersp retation and creep) 80% of aeolian transport in the form of saltation SALTATION DOMINATES. Reptation Creep: Particles rolling or sliding along surface Driven by impact of saltating particles Accounts 10-15% of aeolian sediment transport. How do we calculate aeolian sediment transport? - Q MODIFIED BAGNOLD (1941) Equation Q = Csqrt(d/D rho/g (U_* - U_*t)^3 U_* windspeed at height When would you subtract U_*t When U_* is greater than U_*t , otherwise you'd get a negative number. d = mean grain diameter C = constant D = reference grain diameter rho = fluid density g = accel due to grav u = wind velocity u_*t = threshhold shear velocity. How do we measure Q? Measure wind speed Trap sediment? Anemometer Also use Windtunnels Factors influencing wind erosion/sand transport air ground and sediment Controls on transport: Moisture content: higher threshhold velocity required to Vegetation: Extracts momentum from wind leading to reduced transport rates Total force: imparted to surface equal to sum of forces on roughness elements (F_r) and intervening surface (F_g) F = F_r + F_g Displacement: Isolated roughnness - Each element has own independent turbulence Wake interference Flow - Interaction between turbulence of adjacent elements Skimming flow - Turbulence envelops entire surface and flow displaced (d) above structures Wilson (1972) aeolian bedform hierarchy Ripple-dune-Draa Wilson stated that for any given feature (rpple dune draa) a larger particle size is-... DRAA: A large sand dune hundreds of miles long and hundreds of feet high, often with smaller dunes that form on the leeward and windward faces. While little study for DRAA forms has occurred, Draas appear to be structureally analogous to dunes, but on larger-scale and are considered to be slower moving and older. Depositional landforms Sand Ripples: Series of crests and torughs created by saltation of individual sand grains Forms at right angles (Transverse to the wind) When a wind or water current flows across loose sand, sand is dragged-... Both dunes and ripples are bedofrms (Aeolian and fluvial) All bedforms created by instabilities, in which small disturbances are amplified as the wind blows over the ground. Ripples Formation of ripples is closely linked to the processess of saltation and reptation Wavelengths of 50-200mm and a height of .005-.010m Asymmetric in xsection w/ a slightly convex stoss slope Crest seds more coase than mean size of surface sand. PG320 for Ripples examples amplitude .01-100cm up to 20cm apart Size fnc. (wind v, particle size, ripple type Most formed by bombardment of sed. Dune: Accumulation of sand-sized particles deposited by wind Sand sea or Erg = Extensive area of dunes Dune initiation: Requires nucleus to disrupt wind and reduces wind velocity for deposition to occur Possible Nuclei for Sand Dune Development 1)Topographic obstacles 2)Smaller obstacles (Pebble or boulder, plant bush, animal carcass, human artifact 3) Remnant of previous bedform 4) Surface irregularities and hollows Thomas 1997; table 17.4 Process: Sed deposited on upstream (Stoss) side building up until angle of repose Granular build up falls down the downstream (lee) side This cycle repeats with each layer preserving the previous one. Flow compression: Flow compresses as the wind blows over a dune owing to topographic influences, so the wind's speed increases as it moves over the dune. Look at slope profile in book Backslope 10-15 Crest Slip face 30-35 degrees. Are there other fluids beside wind that produces these features? Yes, Fluvial. Types of dunes: Barchans, Parabolic dunes, Transverse dunes, longitudinal/linea dunes (seifs), and star Barchans always point down wind. BARCHAN: Limited sand supply, Uni-directional winds Sand crossing crestal zone is trapped on lee slope (slip face) Convex windward slope Steep leeward slope Horns point DOWNWIND Roads covered by sand. Barchanoid - Merged Barchans Right angle to wind More sand than barchans. TRANSVERSE: Formed at right angle to wind Thought to be gradational with barchanoid ridges. Examples of them in Lencois Maranhenses, Brazil PARABOLIC DUNES: U or V shaped Horns point UPWIND Lateral edges anchored by VEGETATION Wind erodes from central zone and deposits on the leeward slope Initiated by BLOWOUTS. EX: Blowout in CAPE COD Bowl shaped feature Barabolics most commonly develop blowouts Dune grows downwind BLowouts are initiated by change in vegetation: Fire overgrazing trampling disease. Soil changes (Intrusion of saline groundwater into root zone) Climatic changes (rainfall or wind) parabolic needs vegetation, often coastal, formed from blowouts. Coastal dunes near corpus christi tx

06MAR18

Channel initiation Channel Head: Threshold transition between diffusive hillslope and advective channel processes qs=KS Convex steady state qs=f(qw,s) convex steady state diffusive = dampening out advective = perturbations grow Landscape equation Geomorphic transport laws: To make predictions of landscape changes, gemorphologists need Conservation equations Mass conservation Partialz/partialt = U - E - Gradient x q_s U: Uplift, E: Erosion, qs: sediment transport. Full understanding of geomorph form Plants and trees act to stabilize hillslopes, breaking down rock but keeping all aprticles in place, leading to development of thick soil mantle. This soil mantle pushes towards more diffusive transport of water Soil strength and vegetation act to resist channel initiation Soil moisture, overland flow, and slope steepness are the parimary forces driving channel initiation. Channels are initiated by hillslope processes not channel processes. Initiated at sites of landslides in steep terrain. Initiation of stream channels marks the transition from where hillslope processes domainte sed transport to where fluvial processes dominate sed transport through channel networks Transition often characterized as contrast between diffusion like hillslope processes driven by grav and dominated by local slope angle, and which act to smooth relief, and channel processes dominated advective transport involving flowing water and thus strongly dependent upon discharge as well as slope. What about the tropics and humid /temperate enviroment? HOF is an ideal model that is only appropriate for un-vegetated arid regions where there is little subsurface flow vegetation and high rates of infiltration interfere with overland flow development. Subsurface Flow Horton's model assumed infiltratied water moved downward under gravity into water table. No lateral flow above water table Interflow: Lateral/Downslope throughflow in the unsaturated zone above water table On lower slopes SEEPAGE or springs will occur as groundwater or interflow emerges from subsurface-> RETURN FLOW Combo of return flow w/ direct ppt = saturated overland flow (SOF) -major component of direct runoff in most vegetated, humit-temperate basins up to 50-60% total storm flows. Very small % is actually HOF. Hillslope hydrology Runoff processes: Horton Overland Flow Subsurface Stormflow, Return Flow Groundwater Flow Saturated Overland flow. Subsurface storm flow - combo of interflow and accel groundwater movement as result of rapid rise of water table adjacent to the channel Return flow -Saturated interflow that returns to surface and begins to flow downslope towards the channel. (Form of overland flow) Saturated overland flow - Channel Development - Rills can't stay as parallel unconnected channels Master rills eventually devlop from rills that become deeper and wider than adjacent rills Master rills carry more water and erode faster creating new slopes directed toward the center Probably only works where vegetation is sparse -Channel initiation is related to convergence of surface and subsurface flow. Channel development Irregular in hillslope causes groundwater flow to move towards depressions Seepage promotes erosion -> Positive feedback Groundwater sapping processes works best in arid regions How did the canyons form? Headwall of Fence Canyon Utah. Note incised contributing stream, alcove, dark seep, plunge pool that is swept clear of debris, and vegetated floor. Relief is ~150m Amphitheater headed valleys. How do these features on the Colorado Plateau form? Crystal growth: Evap or groundwater flows bring water to surface - accelerate weathering. Basalt groundwater sapping - a groundwater controlled process involving localized weathering and erosion through seepage alcove development and 'spring erosion' inr elatively impermeable strata (eg shale) underlying massive and porous/permeable rocks (eg sandstone) causing slumping and 'flowage' of the shale units and thus leading to the collapse of overlying sandstone cliff layers. Basal sapping weathering processes Cement dissolution Frost action Salt xstallization Wetting/drying of shales Headward migration throughflow Theater-headed valleys: The roles of overland flow and groundwater sapping. Caentral thrust in geomorph and planetary science is to link diagnostic landscape morphos to formation processes. A prominent ex is the frmation of amphitheater-headed canyons, in which stubby appearance of valley heads, steep headwalls, and little Shaded relief map of box canyon, idaho airborn laser-swath mapping data were collected by national center for airborn lazer maping. Data have been filtered to remove vegitation Same thing seen in mars Contributing overland streams cannot be neglected in the interpretation of these canyons, as the streams are capable of significant sed transport and bed abrasion. Basal sapping on mars? Mars odyssey THEMIS infrared image Large great enough to stretch from NYC to LA. Amphitheater headed valleys (Summary) -Basalt or groundwater sapping + Throughflow -Overland flow -Extreme storms Headward erosion Cannel devlopment Through rapid headwater erosion, a stream may breach a divide, intersecting another channel and capturing its flow - stream piracy. Stream Hydrograph - Represents Rainfall - Hyetograph Look at Discharge (cfs) vs Time(hrs) from midnight, june 21, 1972 in textbook (GRAPHIC) Lag time: Center mass of rainfall to center mass of runoff. Know hydrograph and how to read/draw it Discharge (m^3/s) vs Hours from start of rain storm Storm hydrograph A conceptual summary of factors regarded the development of water rellency in soils following wildfires Could impact overland flow. Storm hydrograph Falling/Recessional limb Baseflow:Continuous input of water from groundwater. Baseflow > throughflow > overland flow > flood stage Controls in Water Levels: What controls the shape of the floor hydrograph. Permeability of rock Vegetation and soil reduces overland flow, increases through flow Sloping (Gentle vs sleep) affects is Was it already wet? Whats the shape of the drainage basin? 'Flashy' look if just basement rock, sharp peak Very gentle bell shape for vegetation&Soil Area, Shape, Slope, Lithology, Soil type and thickness, Land use and land cover Rock type - Permeable rocks mean rapid infiltration and little overland flow, therefore shallow rising limb Deset: No infiltration. Desert Ephemeral stream in flood. Soil - Infiltration generally greater on thick soil, althrough less porous soils, eg clay act as impormeable layers Landuse - Ubranization: Conceret and tarmac form impermeable surface creating a steep rising limb and shortening time lag Afforestation - intercepts precipitation creating shallow rising limb Urbanization leads to Flashy Discharge Peak Drainage density - Higher density Discharge vs Time graph. Pg 173? Stream Ordering Two fundamental concepts introduced by Horton (1945) -Stream order: Tributaries originating at a source are order 1. Two order 1 streams meeting produce an order 2 stream and so on Drainage density: ean length of stream channel per unit area Stream ordering in itself is not very useful but can be used to project phys, chem, biological characteristics of individual stream First-order stream tend to be numberous, short in length, have high gradients, large substrates, and have low discharges Higher order streams tend to be few, longer in length, with lower gradiants. Small substrates and high discharge. Discharge q = av = wdv Discharge of stream at a point along its course amount water pasisng through cannel cross ection point during specificed interval of time Q = discharge m3s-1 A channel xsectional area w is width d is depth v is velocity. Velicity-area method: Measure vel at number of depths and average for a number of sections across river Rating curve use river height as a means to predice discharge based on observed relation between surface elevation and discharge.

23JAN18

Columbia school 'main university of Geomorphology' Driving forces - Tectonics, Climate, Gravity, Exogenic - operate at or near surface, gravity and atmos Endogenic - Energy located inside earth Combination - Volcanic cone as result of volcanism (endogenic) and slope process (exogenic) Climate: Most EXOGENIC processes driven by climate. Global imbalance in solar insolation leads to atmospheric circulation . that result in variation in climate w/ lat Climatic geomorphology: Processes vary by type and rate by particular climate zone. Variation w/ resisting forces (rock types, etc), lead to local exception of the rule. Gravity - Force of gravity applies continuously to all elements of earths surface. Important component in mass movement, fluvial erosion/deposition, glacial movement erosion, tides Increase in slope leads to increase in grav. Internal heat. Convection w/ fluid asthenosphere Uplift: Landscape denudation (wearing down) depends on balance of erosion and uplift. Equilibrium when erosion and deposition perfectly balanced. Volcanism: landforms based on the magma type: Low visc vs high visc. Eruption types explosive volcanos w/ high visc , Creates new land that subjected to weathering. Resisting force: Structure and lithology. Rock type determines resistance to deformation. Differential weathering (breakdown of rocks) leads to topographic variation at range of scales. Structure: Internal structure of rock determines resistance to weathering Neocatastrophism - Contemporary alternative to uniformitarianism. Rare high magnitude events have played an important role in landscape evolution. Landscape evolution: The last 3 principles of uniformitarian philosphy sparked early debates on frequency and magnitude of meomorph processes. PROCESS RATE AND STATE. Gradualism implies change in slow, steady, and gradual... No catastrophies. Drastic changes could occur infrequently RARE AND LOCALIZED> For a channel to change would need flooding* Amazon more or less the same. Bankflow Discharge Magnitude and frequency typically inverse High-Low Low-High. Large magnitude events are spectacular but it is the events of low to moderate magnitude and frequency that do the bulk of the work CONCEPT OF EQUILIBRIUM Static, steady state, dynamic, metastable, dynamic metastable. Concept of threshholds: Intrinsic, extrinsic (internal vs external) Concept of time: Steady, graded, Cyclic. Episodic erosion & Complex response A geomorph threshhold is a point at which a landform becomes unstable. Intrinsic threshhold indicates that changes are possible independently within the system Extrinsic threshhold indicates change brought about by change in an external factor Extrinsic rocks falling into a river Intrinsic: Angle of respose of slope too steep and collapses. Extrinsic threshold. Increase w. external stress (Heavy rains associated w/ hurricane) Intrinsic threshhold: Release of cumulative stress (Buildup of rock debris. On diagram sheet, on the right side, the two by elevation vs time A is a complex response, while B is an episodic erosion. MOST IMPORTANT CHART IS THE DYNAMIC METASTABLE EQUILIBRIUM INVOLVES THRESHOLDS. THOSE SUDDEN DROPS ARE THE THRESHOLDS! Reaction and Relaxation. Response of landscapes and geomorphic systems often occurs over longer time periods than the duration of the disturbance. Reaction time: Interval between disturbance or change in controls and observable morphological change Relaxation time: The ensuing period of adjustment up to a new equilibrium or another geomorphic threshold adjust. Coastal Dunes: Barrier islands w/ well developes dunes are less sensitive to small storms as long as dunes are large and continuous Longer to react and faster to relax Entrenched river created by constant tectonic ulift. Graded stream example of equilibrium creased by a negative feedback Feedbacks Positive feedback: Amplification away from equil growth and decay Negative feedback: Dissipation, towards equilibrium, stabilization. Geomorphic processes operate with periods of quiet, interspersed with periods of rare (low frequency), large events (high to medium megnitude) in a step-function behaviors that includes threshholds as well as such concepts as episodic erosion and complex response. Eruption of mt saint helends influences geography. Lots of ash and lahars move into rivers. "Process Linkage" from volcanic action -> Hill slope processes and mass movement (Debris flow, mudflows) -> Fluvial, hydrologic, lacustrine and biogeomorphic changes. NEXT LECTURE TECTONIC GEOMORPHOLOGY. ALL JUST GEO STUFF Diastrophism Large scale deformation of the earth which p[roduces the earths mountain ranges and ocean basins. Five major classes of diastrophic movements. Orogenic, Epeirogenic (Broader flat), Isostatic, Igneous, Eustatic (Sea level) Either major topographic elements of the earth Ocean ridges/rises. Mid-Oceanic Ridges -Rift Zones-Spreading Centers Transform Faults or strike-slip faults Mid Atlantic Ridge, East Pacific Ridge, Icealand, Easst African Rift system - Triple Junction San Andres Fault. OCean Basins - Abyssal Plains Continental Shelf, Slope and Rise - Submarine Ocean Trenches, Island Arcs, Marginal sea basins. 7)Folded mountains, fold thrust compress uplift of sed rocks, with associated volcanic and igneous activities. Deep scale meta. Milalayas alps rockies young, appalachians, urals old. 8) Continental platforms. Stable continental shield regions- areas of low relief and commonly low elevation of central continental location composed of ancient metamorphosed intruded rocks, places overlain by wedges of undeformed sed rocks.

03APR18

Fan area is empirically related to area of drainage basin according to eq Af=C(A_d)^n Af = fan area Ad = drainage basin area C = constant varying with rock type and confinement n slope of regression line 9. Size of alluvial fan depends on: Area of Drainage Basin Climate Rock Lithology in the drainage basin Tectonic activity Space available for fan growth Climate plays an important role in fan size: Determines Discharge of streams (Q) Frequency of storm surges Weathering characteristics. What is Qe in humid environment? The normal amount within/before Bankflow. Trench - The cut of a river? Degrading. Lithology - Rocks in surce area (Drainage basin) determines rate and character of sed supply Coarse Sed loads build steeper fans Large sed supplies build bigger fans Alluvial fans are best developed in arid areas and are pronounced in SW deserts of the USA Things you want: That asymmetrical sort of horst/grabbin environment Why is arid sw so good?: Lack or scarcity of vegetation means that channels can shift Occasional heavy thunderstorms evacuate highly sed charged masses of waters from mountains Arid zone weathering processes may produce considerable quantities of coarse debris Tectonic and climatic changes have been instrumental in causing changes in base level What are some of the weathering processes here: Winglass canyons and fault-controlled mountain fronts in DVNP, california Faulting continually uplifts front of canyon so that erosion doesn't have time to widen it. Consequently, the canyon mouth retains a steep and narrow shape. Primary geomorphic processes: 1) Channel Flow 2) Mass movements -Rockfalls -Slides (Rock or debris) -Flows (Debris flows) Climatic and tectonic effects on fan development Moist periods - greater sed production = fan aggradation Dry persiods = Channel incision and gullying = fan degradation. Bajadas - Friendly fans growing against eachother adjacent? Modern alluvial fan processes Fan Apex = Trenching, stream flow Mid-fan = Debris flow Distal fan = Braided Channels, Mud flows Intermingling of Distal fan deposits with playa sediments. Figure 14.2 Idealized diagram of the depositional subenvironment Upper fan gravel and blocks Mid fan gravel and planar xbedded coarse-grained sands Lower fans planar and trough xbedded sands, massive or laminate mud flows. Figure 14.21 in handout. Precursor stage, Stage 1, stage 2 & 3 Talus means precursor? t = time u = uplift cd = channel downcutting pa = piedmont aggradation pd = piedmont degreadataion Two general types of Pediments: Glacis Pediment or Caprock - Found mostly in area of duricrusts and other sed caprocks such as in shields and platform deserts - eg australia Sahara (French term, nothing to do with glaciers. 'Glassy, shiny') Rock Pediment - Found mostly in areas characterized by intrusive igneous rocks such as granite, diorite, quartzmonzonite, etc Glacis D'Erosion - First described by French Geomorphologists from the Sahara Desert -These landforms truncate weak materials and tend to be veneered by alluvial gravels - they truncate softer rocks (eg shales) adjacent to a resistant upland (eg sandstone) A pediment is a gently sloping erosional surface or plain of ... formed by running water in arid or semiarid region at... receding mountain front. A pediment is underlain by bedrock... Typically covered by a thin, discontinuous veneer of soil and alluvium derived from upland area. Much of this alluvial material is in transport... Granite Mountains Pediment, Mojave Desert CA Processes responsible for (rock) pediment formation Lateral Planation or Erosion by a stream 2) Sheetwash or sheet erosion Removal of thin layers of surface materials more or less evenly from an extensive area of gently sloping land, by broad continuous sheets of running water rater than by stream flowing in well channels. 3) Rillwash or Rill Erosion Development of numberous minute closely spaced channels resulting from uneven removal of surface soil by running water that is concentrated in streamlets of sufficient discharge and velocity to generate cutting power. 4) Mountain front retreating by weathering 1) Lateral Bank Instability, aided by sparsely vegetated, non-cohesive sed, aids in steram flow bifurcation and decreases the erosivity of discharge 2) High infiltration rates reduce magnitude of runoff and flow distance reduce downstream power 3) Non-cohesive sediments promote slope-driven non-fluvial sed transport by rainsplash, which tends to fill existing rills and incipient channels (before they can erode) Aridity limites weathering rates and vegetation cover. Aridity promotes bare-bedrock uplands Aridity often provides conditions for weakly consolidated soils and regolith. High infiltration capacities and localized storm footprints that favor diffusive smoothing by fluvial processes. Can you have fans and pediments together?

01FEB18

Gruss - As granite is weathering the magnetite, bt, feldspar, what is the process name? Hydrolosis. Chemical Aids physical, physical aids chemical. Frost Weathering (Hydrofracturing) Mechanical breakdown of rock by growth of ice within pores and discontinuities of rock subjected to repeated cycling freeze and thaw (vol expansion of 9.05% Frost Wedging, Talus Slopes, Frost Heaving, Patterned ground & felsenmeer. Felsenmeer = Rock sea. Think a literal coating of rocks over a large surface. A 'Block Field' Starts at the minerals. Growth in Voids: Frost action: Water expands ~9% of vol as freezes and exerts mechanical stress Water freezes at rock surface 1st captures water below. Can reach 20mil kgm^-2! Icy xstals preferentially form. Frost Shattering and Debris Flow Thermoclastis "Insolation Weathering" Breakdown rocks as result of volumetric changes from thermal (heating and cooling_ expansion and contraction Most likely affects individual minerals and leads to granular disintegration Rocks and forest fires (Also lightning). Deserts (hot dry) also places Different rocks respond differently to heating Rocks and minerals expand in response to intense heat. Al minerals have different coefficients of expansion. Stresses result from low thermal conductivity of rocks. Prevents inward transfer of heat. Different stresses cause rock interior to spall off Similar to exfoliation (onion-skin) weathering Thermal expansion: Adding water speeds up the process rapidly. Salt Weathering - Varies w/ salt type. Sodium Carbonate > Magnsium Sulfate > Sodium sulfate Formation of minor weathering features such as Tafoni Holes or depressions that form on the undersides of rocks or on steep rock faces Salt Sources Sea Spray, Seawater, relict sea water, volcanic gasses, rock weathering, aeolian dusts, groundwater. Growth in Voids ; salt action - Salt percolates in fractures Minerals/salts precipitated Intense pressure created through crystallization (Greater than ice) Common in Arid and Semiarid regions where ions (Salt) aren't leeched Controls: Temp, chemical, Mechanical processes: Hydration of salts - absorption of water under low T and high humidity Expansion of salt: Changes in T cause salts to expand. Halite 0.5% increase in volume as temp increases from 0 to 60c Granite increases only by 0.2% over same temperature range Salt crystal growth - Crystallization of high concentration leds to large crystals grow fast. Growth of salt crystals - most effective of all the above. When saline soln in rock pores become saturated as a result of changes in temperature or evap. Sodium Sulfate most effective at weathering. Dolorite - British word for Diabase. TABLE 4.2 Geomorphic effects of salt-weathering processes. Abrasioin: Removal of outer minerals through impact forces Dust emission from clay-crusted surfaces in arid environment Ventifact. Chemical Most important agent is water (slightly acidic), Exchange of cations and anions Role of water is complicated because it is not chemically pure. Contains a number of ions from atmosphere or other materials Organic processes add gases and organic acids to the system. What are the four major chemical weathering process? Solution Hydration Hydrolosis Oxidation Reduction Biological? Kilation Solution: Basically, Mineral + Water Hydrolysis: Chem addtn of H_ or OH- ion in water into internal structure of rock to produce new mineral )H+ is aggressive and displaces other cations Can work in neutral water if there is continuous leaching but works best under acidic conditions. Most important agent in decomp of silicates (such as granites) Metalic cats are seperates from minerals structure and replaced by H+ Depends on fresh water, H+ available, production of organic, acids, easily replaced cations are present, precipitated ions are insoluble, solvent not reached saturation Going to cut out the soils, no soils. Hydration: Expansion occurs when mienrals formed when altered by addtn of water to structure. Mechanical stresses w/ water forces mins apart Begins as a chem process called hydration- formation of clay mins. Bentonite (The common name of expansive montmorillonite) Gruss/Saprolite is formed by disaggregation of granite. Expansion of Kaolinite by differential weathering of mineral constituents. TABLE 4.1 expansion fo common clay minerals by hydration Big Bend national park in texas. Biotic Weathering Plant root growth can open and exert stress within rock fractures Burrowing animals such as earthworms, termintes, ants, moles etc churn seds and increase air and water flow (bio-turbation) Chelation: Chem weathering by plants Incorporation of metallic cations into hydrocarbon molecules Soils which plants growing and decaying contain complex compounds that can chelate metallic cations Lichens also extrete chelating agents Microbial weathering fungi & algae Burrowing animals and plant roots. Microbes and vegitation (rhizophere) release oganic acids -Facilitate hydrolysis of minerals - complex ions within the mineral and help their release. K release from biotite is faster. Microbes and vegetation change soln pH that strongly affects silicate and carbonate weathering Microbial metabolism enchances regolith (especially soil) CO2 levels carbonic acid Produce acid and alkaline compounds that affect soln pH Catalyze oxidation-reduction rxn of metals Leaching: Movement of water and dissolved mienrals through weathering zone. Removes weathered materials and provides new H+. Introduces new ions and clays to different area of weathering zone Without leachign weathering zone is closed system. Arid environs little leach highly mobile ions Humid large leaching removing highly mobile ions in soln.

13FEB18

Karst Geomorphology. Terrain w/ distinctive characteristics of relief and drainage arising primarily from soln of soluble bedrock by natural water. Carbonation sinkholes karsts caves stalagtites/mites Maximum dev of Karst. Geology - large units v. pure carbonate bedrock Heavy rainfall - plentiful and steady supply of h2o Steep topo - creates higher energy sinking stream syst for undearground drainage development Tectonic activity - uplift, tilting, faulting, folding limestone beds cause weaknesses and fractures in the rock for exploitation by infiltrating water Vegetation cover - extensivce forests provide high level of organic matter, increasing CO2 in soil as it decomposes Glacial history -deglaciation released great quantities of water to dissolve susceptible bedrock Karst topo landscape formed from dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems w/ sinkholes, dolines, and caves. Karst topo refers to a limestone region w/ specific landscape of pitted, bumpy surface topo poor drainage Pseudo (false) karst - in volcanic terraine. Karse: Landform denudation based almost exclusively on carbonation (chemical weathering) chem weathering joins fractures Hufe requirements for formation [note connection to hydro cycle] Water, Limestone 80% CaCO3, Limestone must have complex network joints, zone of AERATION, vegetation cover providing different acids Features of karsts: Sinkholes, caves caverns, poor surface drainage dissapearing surface streams, underground rivers. SINKHOLES Rounded depressions that form from dissolution of surface carnbonate rocks Collapse dolines Wide range of sizes Fundamental karst unit of erosion and weathering Chains of sinkholes: Uvala Tower Karst Disappearing streams and swallow holes. Solution, subsidence, and collapsed sinkholes. Can see it on USGS sinkholes. tihansky Stalagmite go up, tites go down. Karren in Croatia - Karren general term used to describe total complex of superficial micro solution features of soluble rocks such as limestone and gypsum. Karren are particularly common on limestone pavements. Grykes and clints. Flat are the clints, grykes have the solutional hollowing Formation of Karst Terrain Evolves from fluvial action and the initial formation of dolines Surface drainage is slowly captured by swallow holes and a subsurface drainage develops. Dolines coalesce to form uvalas which in turn expand to poljes Each region has developed its own morphologic signature Roles of length of time style and intensity of energy flow through hydro system. Dolines and sinkholes are the same thing. Uvalas: Series of intersecting dolines Poljes leads to a dry valley, well developed valley lacking a stream. Commonly part of an intricate drainage system which is also dry. Cockpit and tower karsts. Mogotes Mogote - individual hills that make up cockpit karst. Type of tropical bornhardt or inselberg Lechuguilla cave, NM ----------------------- Mass movement and hillslopes "Accoustic fluidization" - talk about later. Mass movement - Down slope movement of rock and regolith near earths surface mainly due to force of gravity Mass-wasting movement is an important part of the erosional process, as it moves material from higher elevations to lower elevations. Importance: Erosion/transport process Engineering problem Human hazard Stress: 3 types Tensile, comprehensive, and shear. Shear is most important in geomorph though. Figure 4.26 Slope processes: Slope deposits and landforms continually acted upon by agens of stree Resistance to mass wasting on slope surface depends on physical properties of sediment (size sorting shape packing) Sed properties determine whether slope will remain stable. Shear strength (S) properties of matter that resist stresses generated by grav forces such as shear stress imposed by grav. In geomorph processes shear stresses imposed upon rock and soil far more than tensile or compressive stresses Res to shear of material depends on many factors but 3 may be id as being of greatest sig 1) Frictional property 2)... Shear strength = cohesion + frictional resistance Shear strength = cohesion + (Normal stress) X (Angle of internal friction). The coulomb equation. S = C + sigma tan (fi)

06FEB18

Leaching - Amount H2O leaching through soil pH determines solub, altered by processes within weathering zone. Not indep variable (feedback), varies w/ inorganic (geochemical) and organic (pedochemical) mechanisms Redox potential Fixation and retardation Chelation Makes immovable ions movable. Bauxite - Aluminum. Rate of weathering: Can be approx by Experimental lab studies (powders accelerated processes ovens - Studies of tombstone weathering, monuments and building stones Studies of dissolved elements in streams Even if controls on weathering kept constant rate of weaathering not necessarily consstant. Depends on sediment mobility and erosion from site. Rock insulated by upper layer of weathered materials experiences a slower rate of weathering Difficult to measure : Not continuous process, water not chemically pure, can lab studies be scaled up to geologic time? Products and landforms of weathering: By products: Clay minerals, hydrates Silicates arranged in sheets. Ganular disintigration: sediment production - gruss. Makes soil. Rock coatings - rock varnish Landforms: Weathering pits, spheroidal weathering, cavernous weathering, inselberg )deep chem weathering and stripping) Landscapes: Karst, Karren Table 3.4 Common indices of weathering intensity used to date geomorphic surfaces Regolith: Weathered mantle that isn't soil yet Weathering Landforms Inselberg: Isolated hills developed on massive rocks that rise abruptly from the surrounding plain. Formed through unloading and or chemical decomposition either at the surface or below ground. Uluru - Classic inselburg. Domed inselberg or bornhardt - olgas in Australia boulder inselberg or tor - such as granite boulders at Joshua tree national park in southern california. Figure 5.9 a-e Figure 7.6 Formation of boulder tors. Joshua Trees in Mojave desert. Pressure release (unloading) exfoliation. Bornhardts mostly conglomerates. Cavernous weathering. Most processes include some combo of grranular disintegration of feldspars, hydro-fracturing, leaching of solub minerals to weaken rock fabric, SALT weathering, and biological weathering (algae, lichens and fungi - biolithonts) Tafoni - the honeycomb weathering. Weathering Pits or GNAMMAS - depressions in rocks which can contain water, soil and vegetation. Could be relatively flat, circular, or irregular. Duricrust - Resistant Layer left behind after leaching. Causes accumulation of iron, aluminum oxides, silica, caco3, or less commonly gypsum May be made by removal of other materials to leave an enrichment of the crust-forming minerals or enrichment caused by deposition from surface water or ground water, lacustrine or of wind-born minerals, which can then accumulate and form a duricrusts. Calcrete; silcrete; ferricrete; alcrete; gypcrete. See fig 3.12 occurence of duricrusts. Duricrusts are formed pedogenically (within soil) and non-pedogenic (deposition by groundwater and in lacustrine or fluvial environments) Impart relief in form of tablelands, buttes, and mesas, such as in Australian arid zone. Erosion of duricrusts provides coarse debris. a: Patterned ground B: Australia has Gibbur dunes Rock Coatings: Varnish, case hardening, silica glaze, various carbonate, evaporite and iron thin films, as well as lithobiontic or biofilms (organisms forming rock coatings), among others. Table 7.3 Major categories of rock coatings. Case Hardening - production of resistant weathering rind on rocks and outcrops, minerals caused normally by iron or manganese. Coso rock art district. Rock Varnish. <0.5mm coating on rocks that is composed of clay mins, manganese and FeO and trace elements. Modes of formation: Physiochemical, biochemical, other? Paleoenvironmental indicatiors? Varnish micr-laminations High Mn/Fe - Humid conditions (less alkaline_ Botryoidal vernish; Mn rich = Black (also Ba-Barium) Low Mn/Fe = more alkaline, arid conditions, lamellate varnish; Mn poor = Orange. Minimal Mn in earths crust.Where does it come from? Possibly a microbrial bacterial thing.

05APR18

Nahal Yael, Negev Desert, Isreal AP Schick and Colleagues Only 20% of rainfall events initiated runoff. 5% of runoff exited the basin Basin isn't in steady state, but is currently evacuating sed accumulated during periods of more rapid sed generation and lower sed yield. Data indicates that 1) Sed leaving basin derived primarily from hillslope colluvium 2) Bedrock weathers More rapidly beneath a cover of colluvium than when exposed, and 3) Long-term erosion rates of granite, schist, and amphibolite are similar. In model (Modified from Bull (1991) ) change from semi-arid late Pleistocene to hyper-arid early Holocene climated reduced vegetation cover, increased yield of sediment from slopes, and accelerated aggradation of terraces and alluvial fans. https://ars.els-cdn.com/content/image/1-s2.0-S0277379113001303-gr10.jpg -------------------------- Start Aeolian Geomorphology CH8 Aeolian processes: Found in regions of earth where erosion and deposition by wind are the dominant geomorph forces shaping the force of the landscape Distribution: Arid Semi-arid environments -Beaches, Glacial Outwash, Alluvialk fants/playas Enviros where sed have been recently deposited or disturbed. Aeolian GEOMORPHOLOGY a) Wind processes -Entrainment , movemnt b) Wind deposition -Sand Dunes Sand Seas (ergs) c)Wind erosion -Abrasion and deflation -Ventifacts and yardangs d) Aeolian dust and dust deposition Table 1.5 Arid zone landscapes (in different regions Luss - Aeolian silty clay Aeolian sed transport models Von Karman (1881-1963) Boundary layer theory; THE WIND!!! -> Bagnold (1896-1990) Physics of blown sand THE SAND!!! -> Chris Houser? Why study Aeolian Sand and Dust? Dry (Arid) and semi-arid climates occupy 35% of land surface Wind has large impact on erosion and shaping the landscape in arid locals -Soil erosion -Agriculture -Health -Ecosystems -Economic Losses -Climate Deserts are optimal environments for sediment transport - and sources for dust -Dust - Environmental and societal Hazards Processes: Wind-related processes -Moving air causes 1) erosion 2) Transportation, 3)Deposition (landforms) -Interaction of fluid (Wind) and boundary (Sand, sediment) -Air is similar to water, except Is a thinner fluid About air: Air is less viscous than water Less dense than water Buoyancy forces in air lower than in water Critical shear stress for grain entrainment in air is higher than in water Grain settling velocities in air are higher than in water Boundary layer is much thicker Surface Wind Wind almost always turbulent and consists of eddies of different sizes that move w/ different speeds and directions Wind profile is logarithmic and is characterized by the Prandtl-von Karman equation u = u_*/k ln(z/z_o) and u_* = sqrt(tau_o/rho_a) The shear velocity is proportional to the shear stress at the bed See Height (cm) log-scale) vs Wind velocity (cm/sec) in the book. on page 310 Change all V_* to u_* In fluid dynamics; von Karman constantly (or Karman's constant) named for Theodore von Karman is a dimensionless constant involved in the log law describing distribution of longitudinal velocity in the wall-normal direction of a turbulent fluid flow near a boundary w/ a no-slip condition. Equation for such boundary layer flow profile is... U_z = (U_*/K) ln(Z/Z_0) U_* is shear velocity 1 Z_0 is roughness length (height above surface when wind velocity is almost zero. 2A flat, bare surface: Roughness length close to bed. 3Vegetated surface roughnes length higher above the bed 4. No matter how strong the wind blows all velocity profiles will converge to same roughness length value 5) Y intercewpt of velocity profiles Bed roughness Smooth bed: Sed <80 microm Rough bed: Sed >80Microm For given surface velocity profiles tend to converge to the same intercept (roughness length, z_0) regardless of wind velocity On sand surface the rough length (Z_0) is 1/30th the mean particle diam Bed roughness: For rougher surfaces roughness length depends on shape and sitance between individual particles to a max of 1/8th the particle diameter Exact nature of relationship between z_0 and particle size is poorly understood. Fig 10.6 concept of zero plane displacement f (ZPD) or different surfaces Shear stress controls sand movement 1) Shear stress is the net downward momentum exerted on the surface 2) Principal factor controlling sand movement is the shear stress exerted by the wind. As wind speed increases so does the shear stress being exerted on the grain. As wind increases, loose particles will be subkect to increasing stress stress and will eventually be entrained. The critical velocity at which grain movement takes place is known as the FLUID THRESHHOLD 3. When particles start to move ... The bed is bonbarded with greain and this initiated further movement so that sed movement can be maintained at lower velocities. Creating a new threshhold, the IMPACT threashold Pg313 See chart in text book: Values of U_*_tau (cm/sec) vs Grain Diameter (mm) Difference vs hillstrojm is much smaller sediment sizes What is lowerst u_*_tau to entrain particles? ~16cm/s which entrains sand. The graph shows 2 threashhold velocity lines for sand: The fluid threshhold applies to wind moving over a surface when no particles are in motion. Once sand movement has begun, the impacts of grains colliding w/ surface puts other grains into motion. Less wind energy needed to keep sand moving after some grains are in motion and the impact treshhold is Approximately 80% of the fluid threshhold. 2nd equation u_*_tau = Asqrt(sigma-rho/rho(gd) sigma = grain density rho = air density Calculating sediment transport

27MAR18

USGS braided vs meandering W Whats a region you'd find braided streams: GLACIAL Anabranching/Anamostostizing. Makes little islands inside the branches. Anabranch: Channel that separates Island Cutoffs Straight Meandering Braided Anabranching Pg252 variables for different river forms. Distinction based on slope: For same discharge, braided rivers tend to have higher slopes than meandering rivers. https://ars.els-cdn.com/content/image/1-s2.0-S0169555X06002583-gr7.jpg 'This is a Tennessee stream' Pg 258 Nice summary. http://images.slideplayer.com/16/5162815/slides/slide_10.jpg Be able to compare meandering to braiding. ------------------------------- Floodplains Originate form lateral migration of meanders by oeriodic overmank (vertical) flooding Sed composing floodplains rte mainly laterally accreted point bar deposits + Thin veneer of vertically deposited seds (silts clays) during overbank flooding Channel type deposits: Point bars, chutes, meander scrolls (oxbows), channel lag, fill, clay plugs Overbank deposits - Natural levees, crevasse splays, backswamps Other-Colluvium/debris from valley sides Remember load types Stream terraces: Abandonded floodplains formed when rive flowed at higher level than at present. Causes of stream terraces: Rapid uplift, drops in base level, or climate changes. Occurs when river rapidly cuts downloads into its own floodplain. Sudden change from deposition to erosion. Alluvial Terraces form when aggrading river loses its sediment input and begins degrading its bed, leaving terraces behind as it cuts deeper into its sed-filled valley. Depositional Terraces and erosional terraces. Doesn't really care much about it, confusing. Levees: Normal flow water and sed resticted to channel Floods: Water and sediment spread outward from channel Repeated floods: Build the levees and build the channel vertically River can be elevated above surround landscape http://www.coolgeography.co.uk/GCSE/AQA/Water%20on%20the%20Land/Meanders/Floodplains%20and%20Levees.jpg Sacramento River, CA, Floodplain with levee. Levee failure following Hurricane Katrina in 2005. Total Cost 108bln Crevasse splay: Cuts through levee allow sed to spill across floodplain in broad fan-like shape. "A cut/crack" in a glacier. Creates an avulsion. Avulsion rapid abdanment of river channel and formation of a new one. Result of channel slopes much less steep than slope that the river could travel if it took the new course. 1993 Mississippi Flood. Pg299 Deltas - Distribution systems. Three types: River dominated - River discharge dominates - Mississippi Tide Dominated - Wave Dominated - Also possible Combination of both Louisiana coast should be growing, but it isn't despite sed load. Why? So whats happened to the sed load? Dams and barges. Oil and gas in Louisiana. When extract oil and gas, subsidence. ---------------------------------- Desert landforms not on this exam. Ch 7 ends on 283. So don't worry past that. Mountain, Piedmont, playa Fans in China. General Characteristics. What is happening to this fan 'This channel is down cutting, so far now is being downcut, not being build. Fan is high and dry' Deathvalley is mostly pulvurized meta-sedimentary rocks. Alluvial fans best developed in arid areas and are especially pronounced in SW deserts of USA.

07FEB18 (LAB)

Why could it be an increase in height? Say 5 was level, so take rod up hill, now at same place it's a 4. Because the rod is moving, not the scope.

24JAN18 (LAB)

You have to get the textbook! Look at syllabus for lab. Maps are 10ft contours

12APR18

http://www.thegcr.org.uk/GIA/28/Figures/JPEGsHiRes/GCRv28c05f015.jpg Holocene dune feidsl of the pacific coast: PAtric Barrineau, Vatche Tchakerian, and chris houser The dune fields developed in response to the uplifting of the continental boarderlands along the active pacific - NA plate boundary and delivery of eroded sed to the coast where it was trapped between headlands on eather side of the basins (orme and tchakerian, 1986) Conceptual model of CA dune systems showing relatively downwarped basin, uplifted headlands, prevailing winds and 4 distinct aeolian phases; (I) en echelon Nebkha / foredune (II) active/modern transvere and barchanoid ridges (III) older Holocene/Flandrian parabolic dunes (IV) stabilized/vegetated pleistocene palaeodunes NABKHA: A SHRUB COPPICE, LIKE VEGETATION ANCHORED DUNE. SABKHA - Arid coastal lagoonal place. Saudiarabia for example has a lot. In area w/ actively blowing sand, vegetation canopy decelerates wind to cause deposition in streamlined forms known as Nabkha which may by up to 25-35m long Pismo-oceano dunes Central California, En Echelon Nebkha Longitudinal Aligned parallel to wind; Two Slipfaces Formed from two opposed oblique winds 100km long, 100m wide. Linear or Longitudinal dunes(?) Linear Dunes: Simpson Desert in central Australia Seif or Longitudinal or Linear? What makes this one different? It's kinda a little wavy as it goes along, Seif for sword, curved sword, Seif are the crooked features. Proposal: Non vegetated call it 'Longitudinal or Seif', can use them interchangably But if vegetated then call it Linear. Can go from Barchan to a seif if winds change. Replication: Repetition of the same basic landform - is a striking characteristic of dune fields. Star Dunes: The giant of dunes 3 or more sinuous, radiating arms extend from peak; Results from shifting wind directions. 300-400m high Huge amount of sed, rare on beaches. Dunes: Dune height and spacing are regular Described by power function D_h = cD_s^n D_h dune height D_s dune spacing N - Function of sand supply, wind speed C - Constant Linear Dunes, Namib Sand Sea, Nasa Applied Aeolian Geomorphology -Wind erosion control on agricultural fields Control and mitigation of dust Management of coastal dunes and dunes in semi-arid regions Control of sand dunes and drifting sand in deserts. Sahara-Algeria http://egsp.lyellcollection.org/content/egsp/25/1/33/F11.large.jpg Barchans are fairly fast Toward a genetic classification of aeolian sand dunes Kevin R Mulligan, department of Geosciences, Texas tech university Lubbock, TX Vatche P. Tchakerian, department of Geographgy and geology & Geophysics Texas A&M University, College station, Texas Asymmetric Barchans - Asymmetric by arms Dunes and Ergs Distribution Wilson (1973) id'd 58 sand seas w/ areas greater than 12,000km^2 Largest actve sand sea - Rub' al Khali, Saudi Arabia > then 550,000km^2 Largest inactive sand sea - MegaKalahari, southern Africa with an area 2.5 x 10^6km^2 In North America, Aeolian Sand cover ~2% -Largest sand sea = Gran Desierto Del Alter, 5700 Largest stabilized sand sea - Nebraska sand hills about 50,000km^2 Sand Sea controls 1. Abundant supply of sand-size sediments 2. Wind regime/climatic gradient 3. Topographic and/or tectonic controls. The Issaourag Erg in Algeria: Star dunes over longitudinal dunes. Grand Erg Occidental and Grand Erg Oriental in Sahara Zibar - Lag deposit (especially down Erg) The Sand Luis valley is the largest intermtn valley in the world and features a dry climate w/ long cold winters and short cool summers. Average precipitation in Alamosa is about 8 inches (200mm) Average valley elevation about 7,5000ft (About 2280m)

18JAN18

Leonardo da Vinci first person to talk about geomorphology. Drew first contour map of whole river basin, believed rivers carved their valleys and shaped topography. Arno Landscape. 1473 First 'Pure landscape' note sed rocks. 1450-1700 scientific agrarian and industrial revolutions. Renaissance, trade, commerce, explorations, cartography, awareness of soil properties, mnin, canal building, railway construction. Della Natura de 'Fiumi' (the nature of rivers) first book on rivers by Domenico Gugleimini in 1697 Discusses nature of rivers and parts, motion of water, confluients and estuaries, banks, materials, application Nicolas Steno wrote Dissertationis prodomus. Principal of original horizontality and superposition. James Hutton - original ideas leading to uniformitanarianism - wrote Theory of the Earth in 1795 where he laid foundation of many fundmental principles of Geology. Included chapters on uplift, erosion, and consolidation of rock. Unfotunately didn't communicate ideas well. John Playfair explained Hutton's work. Sicar Point in w. Scottland. Disestablishment of Genesis (1700-1780) exploratory geol provided significant evidence for major changes in Earth topo over time. Geol strata Tectonics Sed transport (Charles lyell father of geology) Catastrophist - Uniformitarian debate (1780-1850) that Earth has had long and varied history Catastrophist - dominated by catastrophic changes Uniformitarians: Earth continually shaped by relatively slow uniform changes. Hutton, Playfair, Lyell Uniformitarianism: Present is the key to the past. History of the earth can be explained from current observations and relationships Uniformity of Law: Natural laws have remained same through time Uniformity of Process: Causes changes are same today as in pass Uniformity of Rate : Changes occurs at same rate as past Uniformity of State: Earth remained in much the same state William Smith - First geological map of Britain Lyell, Author of Principles of Geology (1830-1833) which popularized Hutton's concepts of Uniformitarianism. Louis Agassiz (1807-1973) etudes sur les glaciers, 1840 Alexander von Humboldt (1769-1859) First two volumes of cosmos 1845-1847 later 5 volumes. Unity of nature ment interrelation of all natural/physical sciences. Worlds first bio-geomorphologist. Attempted to unify branches of scientific knowledge. Highlighted connection between soils, vegetation, geomorph, particularlly in tropically environs Modern period (1850-1950) - Gradual change acceptance, catastrophism decrease. Grove Karl Gilbert - First work to systematically discuss weathering and bedrock erosion (debris production mechanisms) as well as erosion and trans of seds in landscape. Also stated fundamental relation between slope, energy available for erosion, and stream discharge Structure Time Process -> Landscapes Gilbert - Hypothesized under any given climate and tectonic setting, landforms reflect unique accomodation between domainte processess and the local geology. In 1860s US launched four surveys in US West. King, Wheeler, Hayden, Powell surveys lasted 1860 until 1879. USGS of territories established act of congress on 2 March 1867 John Wesley Powell, GK Gilbert Clarence Dutton (Grand Canyon), William Henry Holmes at USGGS (also artist) Gilbert is considered father of process geomorphology. Contributed to landscape evol, river incision and erosion, fluvial sedimentation, among others. Thomas Moran, grand canyon of Yellowstone, 1872 Hutton and Playfair influenced Lyell, Lyell influenced Darwin, and Darwin influenced DAVIS who in turn spawned three generations of disciples Theories of landform development Davis geomorphic cycles Continuous sequence of uplift, fluvial erosion, denundation Youth stage, streams become established and drainage pattern develops Mature stage, streams approach equilibrium Old age stage, erosion reduces landscape to near base level Rejuvenation new uplift restarts cycle Graph of this starts with peaks at top left then lowers until asymptotic horizon Valleys slightly under that. Theories of Landform development Penck's theory of crustal change and slope development Criticsms of Davis' geomorph cycle Stated land scopes has a parallel retreat, same slope angle over time Many ideas have been substantiated by subsequent works. Quantitative - Process Geomorphology. (1950s) to present): Research shift to more quantifiable measurement-based research Hypothesis-testing, statstics & study of spacial distribution Became more science and less history Balance of gradual and catastrophic process recognized. Process Geomorphology Major ideals and impetus from outside field. Hjulstrom, Bagnold, Horton, among others Columbia school of geomorph (1950) Strahler, Schumm, Morisawa, Hack and Chorley FPIG - Fluvial processes in Geomorphology. Leopold, Wolman, and Miller (1962) THe physics of blown sand and desert dunes. R A Bagnold. Bagnold one of first use fundamental physics to explain aoelian features. His book remains the standard to this day Channel types. Suspended load, mixed load, bed load.

30JAN18

Framework of Geomorphic (physiographic) Provinces of the United States. Basin and Range , Cascades - Andesitic, rhyolitic, basalt. Sierra Nevada - Igneous, specifically Granite. 'Coastal lowlands' Climate, Process, and Landforms -Morphogenetic Systems Six possible climate process systems. Figure 2.11 Also Table 2.3 Climatic Geomorphology. Major climate change is a THRESHOLD producing phenomenon. Though cause and effect relation may pass through intermediary factors such as sea level flux or biogeomorphic screen including vegetation, soils, and lithology. Effects of climate and vegetation. Langbein and Schumm (1958) - Semi arid region produces highest yields. Sediments can begin to move into a reservoir in the semi-arid region when it rains a bit. Curve can come back up (Knighton, 1998) Sigifican't amounts of rain can change the amount of sediment movement. Figure 2.16 hypothetical flow chart showing how climatic variables-... Start Weathering processes and Landforms. Weathering - process of alteration by breakdown of rock and soil materials at and near earths surface by mechanical chemical and biotic process. Mechanical - physical processes breakdown rock mineral structure or collapse of parent material and diminution of grain size. Chemical/decomposition -Chem rxn that alter rock mineral. Biotic - Plant and tree roots, worms, burrowing Weathering landforms; unique weathering such as inselburg, tafoni, tors, arches, karst, duricrust, rock varnish, others. Weathering has 5 important characteristics. 1. Process which renders resistant rock and partly weathered rock, into a state of lower str and greater permeability which processes of erosion can be ffective 2. Weathering produces seds for fluvial, coastal, glacial, and aeolian sys 3. 1st step in process of soil formation 4. Weathering accumulates or releases in solution lime, silica, alumina, IronOxides, and when these are ceontrated form indurated shells on rocks or layers in soil (Duricrusts) 5. Formation of distinc landforms (tors, tafoni, rock coatings, etc) Banded Iron Formations up North Landslide is Mechanical/Physical. Since its up high, probably ice, fracturing, etc Why do rocks weather? Rocks and minerals are not usually in equilibrium with conditions at or near earths surface. Rock characters - Composition, Consolidation (compaction, cementation and fusion) internal structure, texture (porosity and permeability) II. Environment - Ex: Temp, moisture, time, topography, biological organisms. Most common rocks in earths crust are igneous, most common at surface at: Sedimentary 66% b. Ig and Meta extrusives 8%, Intrusives 6%, Metamorphic 17% Table 1.8 Rocks Exposed at surface of North American continent (percent of area) Cliff formers are resistant, slope formers are weak. Factors affecting weathering - Topography Slope (runoff rates water tabe stability Exposure (temp rain) -Relief (Elevation) Vegetation Rainfall interception: Bare surfaces; rain not interceped creating high runoff and little weathering Vegetation: Rain intercepted higher infiltration and weathering. Organic Acids: Promote chemical weathering Mechanical Weathering. Physcal breakdown and disintegration of rocks. Four types 1. Pressure release 2. Hydrofracturing-frost weathering 3.Thermoclastis 4.Salt Weathering -Abrasion - wind water ice Slaking - Alternate wetting and drying. 1. Pressure Release - Ultimate purpose of it. Granite commonly reacts this way. Removal of overlying rocks, causes v. pressure relieved, hence fractures develop approx parallel to ground surface. Sheeting, exfoliation (Spheroidal weathering), Unloading, Granular disintegration mineral expansion (clays) Hydration (chemical and physical) Gruss. Pressure Unloading: Expansion of large segmets of rock Unloading of this pressure via erosion of overburden causes rock structures to relax unload and expand Release occurs usually along pressure-release joints causing fractures Spheroidal Weathering: Rounding of corners; corners of an outcrop are exposed to weathering on two or three sides. Gruss = Weathered Granite

07MAR18 (LAB)

Fluids: Gas, Liquid Discharge Q = L^3/T Mean flow velocity (U) = L/t Discharge measure: Velocity-area method: Measure velocity at a number of depths and average for a # of sections across river Rating curve Everything should be in m^3 rather than ft^3 Streamline: Path followed by a fluid particle Reorder manning equation REMEMBER, UNITS. HAVE TO CONVERT. Reynolds: Transition from laminar to turbulent. R = A/P don't forget. Flow criticality Critical flow (F=1) Sub critical F<1 Supercritical flow F>1

21FEB18

Eq1 A = B + C eq2 6A=3B+2C eq3 11A=5B+9C 2x(eq1) 2A=2B+2C -1x(eq.2) -6A=-3B-2C For 3&4 continues to C+(gammaDry-Gammawet*m)h_1(Cos(theta))^2tan(pitchfork) /gamma_dry*h_1*costheta*sintheta Gonna need to use trig. SOHCAHTOA q5

(LAB) 28MArR18

Lab 5: Fan Morphometry See alluvial fan table 7.3 if necessary. Fan size dependent on Area drainage basin Lithology Climate (discharge/storm frequency) Weathering characteristics Tectonic activity (Channel slopes) Space available for fan growth. Vegetation Stream Power Basin geometry Do you think a larger gentler basin has more sed potential in storage than a smaller one with steeper slopes. Look at Unit Stream Power equation. What is the necessary requirement for fans.

20MAR18 (GEOMORPH TEST NEXT THURSDAY)

Big Bend for spring break. Very volcanic area Collapsed volcano. What process from bigbend for the resistant layer? Groundwater Sapping. Can see the seepage on the bottom. Landforms? Hiking trail. Loccolith. Spheroidal weathering of the granites qtz monzonites etc. Get lots of Gruss. Also Exfoliation. Sills. Landform name of small granites isolated Tors. Rock Varnish. Mules ears: Rhyolite plugs. GEOMORPH TEST ALSO NEXT WEEK ON THURSDAY. Study Entrainment, Erosion, Transport, Fall Velocity, Deposition chart. Clay Silt Sand Gravel Cobbles/Boulders After Hjulstrom 1983 Pg224 Figure 6.13 Shields curve for entrainment of bed particles where D is grain diameter Sigma, D/deltao tau = roh g d sin(theta) at slopes <10% or 5.7degree, sin angle ~tan theta = S tau = roh g d s For fluid begin transporting sed that is at rest on surace, boundary or bed shear stress exerted by fluid must exceed critical shear stress. Stream Power Bagnold (1966) first proposed that entrainment and transport of bedload can be analyzed in terms of stream power Specific stream power (ohm) or Unit stream power (whomega) or Mean stream power (whomega) power per unit area of a channel in watts per meter (W/m) Can also be expressed per unit bed area if you divide by channel width (whomega = gamma Q S / width Ex: Or does d = diameter? whomega = gamma Q S / width Q = AV = (width distance(diameter?) velocity?) whomega = gamma width distance velocity S / width whomga = gamma distance velocity S (gamma = roh gravity) remember tau = gamma distance slope whomega = tau Velocity ( whomega = tau V (critical shear stress x velocity) Where available stream power > needed to transport stream load, scour of bed alluvium (entrainment) will occur. Can evaluate erosional capability of rivers. Threshhold between channel bed aggradation (deposition) and degradation (erosion) can be defined by ratio of stream power to resisting power - latter a function of sed supply and hydraulic roughness (bull 1979) Sediment transport: Most energy in a Stream is dissipated by the many factors that we have been discussing that resist flow in open channels (Bed-forms, particle size, bed, banks, etc) The remainder (through commmonly small) used in important task of eroding and transporting sediment. How does river carry load: Dissolved load & Suspended load & Bed load Three components Dissolved: Material transport in soln and derived from rock and soil weathering (ion from chem weathering) Atmosphere and human activity (Major contributor is subsurface flow) Suspended Load: Particles of sand , silt, clay carried in suspension. Velocity of water keeps them suspended so they don't fall to bottom. Bed surface subsurface Bed load load: Refers to sed transported close to or along channel bottom by rolling, sliding, or bouncing. Two types: Saltation & Traction. Bank Erosion: process of entrainment determine the types and magnitudes of erosion that occurs in channel floor. Incorrect to assume only significant erosion is vertical. Bank erosion is importantand controls channel processes through channel width. Occurs through: Fluvial entrainment-sed entrained directly by forces generated in river (corrasion) Weakening and weathering of bank materials - leads to mass wasting. "Remember banking collapse" Three interrelated processes (Morisawa 1968) THE THREE Cs CORROSION; CORRASION; CAVITATION 1) Corrosion - Chemical Action of water 2) Corrasion - Mechnical action of water -Hydraulic Action and Abrasion -Potholes and surface abrasion, armed with seds and particles. Cavitation = Processes associated with effects of shock waves generated through collapse of vapos bubbles/pockets in flow with marked pressure changes. Waterfalls, Rapids. SEE DIAGRAM IN BOOK pg 231 Dissolved, Suspended vs Bedload. A: Transport rate B: Frequency of occurrence C: Product of magnitude and frequency Qe: Most effective transporting discharge Ql entrainment threshold diagram Qe is that which is able to move debris at a moderate rate and that occurs relatively frequently. Subsolar point straight above Spring its at equator, At summer Range is 47 degrees. Pg 234? Stream power in watts per square meter. B is better at eroding bedrock. Deposition: Particles settle to bottom at rate depends on: Density water, Fluid viscosity, size shape density of sed. Rouse number: P = ws/kus Bedload > 2.5 50% sus 1.2-2.5 100% sus .8 - 1.2 Washload <.8 Coarse particles tend to be deposited first as flow velocities decrease may be deposited during minor fluctuations. Constant fluctions in flow make channel floor a dynamic interface where some particles are being entrained while other deposited. Scour and fill depends on local conditions. Stream Competence vs Stream Capacity Competence: Heaviest particles a stream can carry. Relies on stream velocity. Faster the current, heavier the particle can be moved Capacity: max amount solid load (Bed and suspended) a stream can carry. Depends on both discharge and velocity (since velocity affects the competence and therefore range of particle sizes that may be transported) Competence varies ~ 1/6th Most of work of streams ia ccomplished during floors when stream velocity and discharge (therefore competence and capacity) many times their level during low flow regimes. This work is in the form of bed scouring (erosion) sed transport (Bed and suspended loads) and sed deposition) Hydraulic Geometry (Leopold and Moddock, 1953) Pg234 Hydraulig Geometry : Equations describe functional relations of a stream between the Width (w) w = aQ^b Mean Depth (d) d = cQ^f Mean vfelocity (v) v = kQ^m Discharge (Q) Q = ackQ^(b+f+m) Pg234 still another graph. Hydraulic geometry relations of rvr channel comparing variation of w, d, v, suspended load, roughness and slope to discharge at a station or downstream. Good for short term changes - so need to be cautious with over generalizations ------------------------------ PROBABLY GONNA BE A TEST QUESTION Long and cross profiles on a typical river (USGS GRAPH!) Upper valley, middle reaches, lower reaches http://www.acegeography.com/uploads/1/8/6/4/18647856/895888_orig.jpg -------------------------------- Graded profile changes GRAPH any change to graded profile eliminates earlier conditions of KNICKPOINTS. More resistant strata, nickpoint, waterfall https://laulima.hawaii.edu/access/content/group/2c084cc1-8f08-442b-80e8-ed89faa22c33/book/chapter11/nickpoint.jpg Want to change river profile: Use Base level drop Tectonic activity Erosionally resistant rock Elevation vs Distance from drainage divide Slope = 100 to 10% debris flow dominates Now River flow dominated 10 to 2% shallow flow over boulders 2 to 0.1% gravel bedded rivers <0.1% slope: sand bedded rivers Depositional basin as slope approaches zero. ANGSHOU RIVER, TAIWAN for DEBRIS FLOW DOMINATED CHANNELS Colluvial channeL: Small headwater channels at tips Transitional Channels: Switzerland Erlenbach Torrent Slope >2% Step pool step pool. Thalwig: Deepest part of river bend.

08MAR18

Flow in Open Channel Discharge Q=Av=wdv Q = discharge m3s-1 A = x-sectional area w is width d is depth v is velocity Discharge of a stream at a pt along its course is the amt of water passing through channel xsection at that point during a specific interval of time. Discharge measure: Velocity-area method: Measure velocity at a number of depths and average for a # of sections across river Rating curve: use river height as means to predict discharge based on observed relation between water surface elevation and discahrge. Velocity - pgs 212 to 225 Valocity - quantity expresses movement of fluid in distance travelled per unit time (ms-1) Streamline - Flow of fluid past an obj such that vel at any fixed point in the fluid is constant or varies in regular manner Laminar flow: Occurs when flow streamlines are in parallel layers and are not interrupted by neighboring fluid particles Turbulent: Occurs when flow streamlines are irregular and fluid particles flow into adjacent flow layers Resisting force generated by fluid & eddy viscosity due to larger irregular motions (ie eddies) in flow Rarely see laminar flow in life. Steady flow: Velocity at any fixed point in the fluid remains constant in magnitude and direction through time Unsteady: Velocity at a pt (direction or mag) varies with time - fluid is accelerating or decelerating Uniform flow: No velocity change in magnitude of flow from pt to pt (no accel) and streamlines are parallel Most natural fluid flows are unsteady (velocity vector at a pt changes over time) and non-uniform (velocity vector changes in mag and dir from point to pt) Look at velocity examples by location in book. Reynolds number. Dimensionless Reynolds number can be used to define the transition from laminar to turbulent. Re = rho v R / mu roh is density, mu is visc, v is velocity, R is hydraulic radius A/P, where A = xsectional area, P = wetted perimeter Amount of energy in fluid motion is the prod of essentially 3 forces Initial (via momentum transfers) viscous (particle and bulk fluid interactions) Gravitational forces (acting on a mass) The ratio is therefore the ratio of the forces driving stream flow (vR) and the forces resisting flows (mu rho) Viscosity: Resistance of a fluid to change in shape -Molecular visc: Resistance due to friction between individual water molecules as they collide and slide past one another. Affected by temperature and suspended sed Laminar flow Eddy viscosity: Resistance due to friction along eddy lines Turbulent flow Turbulence: Frequency and magnitude changes in water velocity as water is interchanged in eddies. general rule: As Re up flow becomes more turbulent Molecular (Viscous) transfers become < turbulent transfers (inertial effects) Turbulent Re>2000 Laminar flow Re<500 The threshhold between laminar and turbulent depends on scale of measurement Grain-scale Re uses particle diameter as length variable Zone of max turbulent is near the bottom of a stream but velocity is usually highest at -... Turbulent flow in headwaters of a rushing mountain streamations and resistance Flow velocity is determined by the resistance offered by the channel Chezy Equation - Velocity is directly pro Near-laminar flow in center of a river channel. Could find laminar maybe in very uniform dune sand? Great sand dunes national monument Look at Table 6.1 in the book. Flow characterizations in open channels Boundary Layers Frictional effects cause flow retardation adj to stationar boundaryies. Boundary layer Friction is resistance provided to the fluid motion by irregularities on surface Boundary layer - zone where there is a velocity gradient and viscous and inertial forces give rise to shear stresses No slip condition: Fluid directly adjacent to the wall doesn't move. -Viscous retardation gradually dies out away from the wall until the free stream layer. tau = mu(dv/dy) fig 3.2 theoretical vertical profile of velocity. Flow equations and reisstance Flow vel is determined by resistance offered by channel Chezy Equation - velocity directly proportional to slope and hydraulic radis v = Csqrt(RS) where C is proportionality constant that is related to the resistance factors in the system manning equation -Velocity also proportional to the hydraulic radius and the slope R = hydraulic radius S = slope n = roughness coefficient Can estimate n visually. Fig 9.2 representation of various stream channels with cross-sections and values of manning's n Hydraulic radius - Defines volume of water affected (resisted) by the channel sides Calculated Hydraulic radius = x-sectional area / wetted perimeter. 4 x 7 x 4, gives 28 and 15. Resistance - Total resistance into 3 major compoennts Free surface rsistance: Represents loss of energy resulting from disruption of water by surface waves and abrupt changes in surface gradients Channel resistance: Undulation in the channel bed and banks as well as alterations in channel plan form and cross-sectional shape Boundary resistance: Movement of the water over either individual clasts (Grain roughness) or micro-topographic features such as ripples and dunes (Form drag) Ripples and dunes: Different flow conditions may model bottom seds into variety of bedforms Resistance related to spacing of beforms Greatest resistance occurs where turbulence generated downstream of one bedform is not dissipated before the next bedform Particle size: Grain roughness is primarily dependent on the depth fluow relatie to the size of the particles relative to the size of the particles (Relative roughness) -Larger clasts are associated greater roughness for flow depth Froude Number - Define turbulent nature of a stream: Fr = v/sqrt(gh) v is velocity, g is grav, h is water depth Dimensionless ratio of inertial to gravitational forces in fluid flow. -Indication flow stability or energy level General rule: As Fre increases, Gravitational forces < Inertial transfers in flow. Fr = 1 'Critical' level where flow energy is minimum balance between inertial and grav forces Fr < 1 sub critical or tranquil smooth flow, grav forces dominate (Or streaming) Fr > 1 super critical or rough inertial forces dominate ability to deform water surface ie overcome grav to cause standing waves. (Or shooting) See bedforms chart in book. Table 6.3 Variations of manning's n values with changes in bedforms occuring under different flow conditions. Table 9.1 Values of manning's n for flood-plains and stream channels Darcy-Weisbach equation in book. Fluid flow in rivers - some observations 1) River flow is newtonian, unsteady, non-uniform, turbulent and hydraulically rought 2) Channels resistance and boundary resistance dissipate lots of river energy (also confinement of river) 3) Greater the velocity, > turbulence > erosion 4) The steeper the slope > V > T > E Irregularities of channel bottom resulting from pools, riffles, and bard. Aquatic and stream-side vegetation Suspended sediment: Increase in conc of suspended sed tends to lower resistance As conc increases, turbulence reduced because mixing process in fluid is dampened. Sediment laden water should flow at a higher velocity than clear water. -------------------- Work of a river Entrainment Flowing water exerts shear stress, tau, on particles at the bed Transport occurs when driving forces (shear stress) exceed resisting forces Entrainment: Depends on balance of resisting forces on surface, specifically: Gravity, function of weight particle buoyance effect) Drag (Func particle size, arrangement [eg armouring , contact friction], flow speed\ Lift - function flow turbulence, particle arrangement [eg protrusion] Fd + Fl > Fr Sediment entrainment Amount sed transport related to vel and critical shear stress as well as to: Particle size, shape, packing. Huding effects - small particles shielded by larger ones Sed layering - burial fine particle layer (sub-pavement) by coarser layer (The pavement), hence larger particles more readily exposed to fluid flows Equal mobility concept Turbulent bursting Short intermittened suspension of sed projecting above mean bed level or from the crest of a ripple been attributed to eddies penetrating the bed. Water carried upwards by ejections into faster moving flows and downwards by sweeper into slower-moving flows. Passage of burst over particle causes it to be lifted from bottom and carried into the body of the flow Particle stops rising and begins to sttle bck to the bed as the ejection breaks up Return of grains to bed. Flow separation: Boundary begins to separate from fluid flow Point of separation depends on velocity of flow. Stream Compoetence: Refers to size of largest particle a stream can entrain under a given set of hydraulic conditions Value of competence depends on how sed being moved is measured and how accurately the flow conditions can be determined Difficult because -Particles entrained by combo of fluvial forces Flow vel is neither constant nor easily measured -sed packing and distribution Flow velocity vs particle size Clay, silt, sand, gravel, boulder. Clay tends to aggregate

17APR18

Largest stabilized sand sea (erg) in USA, Nebraska Sand Gills. Can the sand be re-activated? What holds sand together of ancient dunes? Vegetation. Severe draught could do it as well as major grazing from cattle. Done Mobility Index (M) M = W/(P/PE) First proposed by Ash and Wasson (1983) and madified by Lancaster (1988) and Tchakerian (1999) M proportional to percent time that wind is blowing above threshold velocity (W) for sand transport (5 m/s), and inversely proportional to precipitation over potential evapotranspiration (P/PE) Sonoran desert -> Chuhuahuan desert -> Great Plains by wind speed and frequency. Worlds largest sand sea (erg) Rub' Al Khali Composition and Sources of Sand in the Wahiba Sand Sea, Sultanate of Oman Aeolis Mons Rippled surface of 1st martian sand dune ever studied up close fills nov 27th 2015 view of High Dune from Mast Camera on NASA curiosity rover. Site part of Bagnold Dunes field of active dark dunes along the northwestern flank. 'Namib sand dune on Mars Shows downwind side of dune 13ft high. Highest point is crest, break is the brink point where it starts eroding/wasting? Barchan dunes on Mars. Aeolian Erosion Deflation: Removal of loosened material and its transport as fine grains in atmospheric suspension 2)Abrasion: Mechanical wear of coherent material In a veggetation free environment, the relative significance of each of these processes is a function of: a) Surface material properties b) the availability of abrasive particles c) climate The resulting landforms include ventifacts, yardangs, ridge and swale systems (mega-yardangs), and desert depressions (pans) DUST is an important byproduct of some forms of erosional activity. Deflation: Can lead to formation of depressions and pans Ex playa deflation at WHITE SAND NM, New Mexico - 'largest gypsum field' Nebkha - Don't forget. Famous desert depressions of Egypt Initially believe to be caused by aeolian deflation Depressions occur along boundaries of NW-Dipping strata and are bounded to the north by escarpments. More complex origin. Wattara depression Polygenetic origin (mostly late Tertiary and Qaternary) Originally a stream valley and subsequently modified by karstic activity, mass-wasting, deflation, and salt weathering. Aeolian processes active only during more arid phases of the Quaternary Ancient lake beds, dunes, salt marshes and other desert features today. Abrasion effeciency depends on: Particle size Particle Velocity Angle of impact Atmospheric density The greater the kinetic energy as result of alrger grains or higher grain velocities... Ventifacts on basalt, mojave desert, California Ventifacts: Wind eroded rocks of varying scale, form and material composition formed by aeolian abrasion. They include smoothed and polished surfaces, facets, pits, flutes, grooves, helical forms and etching. Ventifact formation influenced by: Wind magnitude, frequency and persistence Sed supply Basin geomorphology Vegetation cover Characteristics of the target rock or surface. Height vs kinetic energy flux (J/m^2s Most of this occurs under 2meters. YARDANGS Geomorphic form similar to an 'unverted boat hull' ex: Yardang field, Dasht-e lut desert, Iran Yardang field, ridges known as yardangs formed by wind erosion. Form in arid where strong unidirectional winds carry sand. This yardang field located in centre of Dasht-e Lut, a salt desert in iran. The Yardangs here reach over 75m in height. Yardangs: Aerodynamically shaped elongate hill oriented parallel to wind OCcur in clusters Need deposits which re relatively friable and easily sculpted, yet cohesive enough to retain steep slopes Best developed in slightly compacted finegrain seds, such as lacustrine silts and clays Also form in broad range of geologic materials. First Yardang national park: In Kumtagh desert in nw. china Ex: Rogers Lake, Mojave Desert, California, Mega-Yardangs: A global Analysis Andrew S. Goudie

26APR18

Abrasion: Removed debris in basal ice grinds into the bedrock like sandpaper. Efficiency of process depends on conc and type of material carried in ice as well as properties (Hardness fracturing of bedrock) Ineffective unless particles continually moving towards bed of glacier renewing force Effective erosion is unlikely to occur unless debric produced at ice/rock interface is evacuated. SEE TABLE 8.1 Groovesw large striations caused by large obj lodged in the ice Fracture of bedrock "Plucking/quarrying" process by which ice of ice/debris exerts sufficient force on bedrock to cause gracture Chattermarks, sheared faces Wedging by pressure of over-riding rock particles Pressure variation at ice-rock interfaces Chattermarks: (Friction cracks) occur transverse to straiations and grooves Due to chipping and grinding schematic diagram showing increasing friction accompanying increasing ice thickness Abrasion rate vs ice thickness. Less thickness increasing abrasion, ice thickness bigger reduction in abrasion Till: What a glacier deposits Moraine: Till that's been shaped into like a ridge Joint exploitation: Exploitation by ice of lines of weakness in rocks Removal of larger blocks of rocks a: Weakening of bedrock before it is covered by ice -Pre-glacial conditions -Unloading b: Weakening of bedrock while covered by ice *tension cracks (Dilitation) Subglacial water action: Meltwater erosion at base of the glacier -Cavitation - pressure differences down/up river resulting in bubbles forming. Like propellers -P-Forms Subglacial dissolution *Chemical weathering and erosion by meltwater -Corrasion, mineral dissolution and carbonation NYE Channels, named after Nye Glacial abrasion (producing striae) and subglacial meltwater under high P give rise to channel-like structures (Nye channels) cut in the bedrock, as the margin of glacier de tsanfleron, switzerland, MH See figure 10.3 for various P forms. Zickemballem(?) Where is best place to see this? Central Park in NYC ROche Moutonne (Rock Sheep) Bedrock mounds w/ steep face pointing in flow direction formed by rock removal on the lee side of an outcrop and abrasion and polishing on the windward upstream side Asymmetric hills formed largely as a result of abrasion on their upstream side (Stoss-side) and intense quarrying and join-block removal on their downstream side (lee side). The quarrying is thought to result from loewr ice pressures found on the lee side of protuberance Figure 10.2 and 10.3 Eratics, random boulder. Cirque A deep, semi-circular erosional depression w/ steep, frost shattered headwalls located at the head of a mountain valley, it is sometimes described as an amphitheater shaped feature floored by a rock basin. Cirque Basin Glacial eroded basin shaped like half a bowl; deep, steep-walled recess in mtn When ice receeds leaves behind a dammed lake or TARN Expansion of cirque glaciers & Activity of slope processes in cirques erodes walls to create remnant feature including sharp horns & aretes Pg371 ON TEST Might ask to sketch/ID zones on FIGURE 10.9 where you'll have to place things like crevasses and such Elevation vs distance to terminus Cirque formation believed to be result from chem and mech weathering (Frost shattering and mass movements (protalus ramparts), including rotational sliding associated with cirque glaciers in the rock basin Combined processes outlined above are referred to as Nivation Might give block diagram and want you to id cirques, lakes (tarns), u shape valleys, water falls, arete, col, gorn, etc (Col is a connection horn to horn) Exhibit irregular longitudinal profiles ("Staircase profile"), riegels and rock bars (i.e. compressive and extensive flow) Mt Conness and Tenaya lake, yosemite national park. Classic alpine glacial features Randkluft and Bergschrund (Crevasses seperating headwall from the glacial. Randkluft is the first one, Bergschrund is the 2nd Gonna as a question about extended and compressing flow Good profile on pg 372 TEST 12:30 THURSDAY Longitudinal cross-section of a valley (alpine) glacier Erosional landforms Aretye Horn Col Tarn Paternoster lakes Cirque UShaped Valley Hanging valley Bargshrund Randkluft Roche Moutonne Moraines Lateral, Medial, Terminal moraines EXAM REVIEW STUFF Extended bagnold equation Law de wall, U*t cubed Glassy pediments 283-297 Know what Loess is and the two mechanisms of Loess formation, ex china vs N.America Then Glacial stsuff ch 9 and then Ch10 362-375 ID a block with arete cirque horn etc

19APR18

PM stands for Particular Matter. Dust particles may remain suspended until Wind Velocities drop and particles can't remain suspended Dust particles collide in the air, and stick together forming larger particles Rain washes dust from atmosphere The dust cycle is an integral part of the Earth system. Each year, an estimated 2000Mt is emitted into the atmosphere, 75% of which is deposited to the land and 25% to the Ocean. Dust carries organic matter and contributes directly to the carbon cycle and transports iron that is vital to ocean productivity and ocean-atmosphere CO2 MAJOR DUST REGIONS Where is the dustiest place on Earth? Sahel the Bodele depression in Chad the brightest region in this 13yr avg of satellite data on the concentration of aerosols Bodele is covered in diatomite, which, when eroded is the source of large amounts of dust. Characteristics of Dust Source Terrains Large basins of internal drainage Presence of deep and extensive alluvial deposits Dry lakes (playas) Dunes or sand sheets Table 18.3 Geomorphological units from which substantial deflation occurs Also FIGURE 14.7 An idealized geomorphic model of a mountain-piedmont basin https://ars.els-cdn.com/content/image/1-s2.0-S0341816211001561-gr5.jpg Figure 12 schematic illustration of relations among potential for dust emission LOESS - Aeolian silt and clay, 10-15% of the world. Aeolian sed formed by accumulation (PG328) of wind-blown silt (sed w/ particles 2-64 microns in diameter) and smaller amounts of sand and clay that are loosely cemented by calcium carbonate It is usually homogeneous and highly porous (near 60^ porosity) and structured such as to permit the seds to fracture and form vertical bluffs or fliffs without slumping Deposit of windblown dust Fine dust in loess typically only 0.01 to 0.06 mm (.0004 to .0024 in) in diameter Two primary sources for Loess deposits Deserts Glacial Outwash Deposits Simplified model of fine (silt-sized) particle production to generate dust in glacial environments Largest Loess deposits in America are from the Glacial part. ---------- Glacial Geomorphology. At present only 10% surface covered by glacial ice Pleistocene 30% w/ 2/3rd of NA under ice LGM last glacial max ~18kyr. Louis Agassiz 1807 - 1873 Table 9.2 Morphological, Dynamic, and Thermal Classification of Glaciers Glacier: Perennial body of xstallized snow and ice that moves downslope and or outward under its own weight. Two broad categories of glaciers: Alpine Continental or Ice Sheets Alpine: Cirque Glaciers - Glaciers in small semi-circular depressions on mtns Valley Glaciers - Flowing down a valley as a result of the merger of two or more cirque glaciers Piedmont Glaciers - Glacier occupying a lowland at the base of a mtn area (Fed by one or more types of valley glaciers, like the columbia icefield in Alberta) Palisade Glacier in California: Tsch first glacier. Rock Glacier Characterized by a large amount of embedded or overlying rock material Ice Sheets now only found in Antarctica and Greenland, enormous continental masses of glacial ice and snow expanding over 50,000 square kilometers (19,305 sq miles - NSIDC) Glacial Balance - Ice Formation - Snow accumualtes in catchment area Snowpack becomes denser over time due to compression by weight Density comparisons Snow -> Firn -> Neve -> Glacial ice (overtime losing air from snow to glacial ice) Heat, water vappour and water are released within snowpack. Causes density to increase as snow converts to firn It takes one year to form firn in Montana while in Antarctica it takes up to a century to form ice. First pages of Glaciers. Glacial Mass Accumulation Zone - Area where snow can accumulate and is not melted in the summer Ablation Zone - Area where snow is melted during the summer Firn Line - Seasonal Boundary between old ice (below) and recrystallized new snow (above) Ice lost in ablation zone -> Firn Line -> Ice gained in accumulation zone. Glacial Balance: Long-term average position of the highest (late summer) Firn line is termed the Equilibrium Line Altitude (ELA): The long term balance point along a glacier The ELA is where the amount of accumulated snow and ablated water are equal The ELA is climate and location dependent -Temperature(Controls melt) -Winds (Controls evaporation and sublimation -Shifts with season and longer term climate change Energy Balance: Short wave radiation from sun Long wave radiation from clouds and valley walls Heat - Conducted from atmosphere Geothermal Heat - conducted from earths interior Latent Heat - From transition of vapour to water How much energy radient is absorbed by a glacier surface depends on reflectivity - Albedo

25JAN18

Plate Margins - Third Order Trenches Ridges Orogenic Island Arcs. 4th order: Intermontane basins, mtn ranges, volcanoes, rift zones. Plate Interiors 3rd order: Platforms, shields, abyssal plains Transform or strike-slip orogenic zones - San Andreas fault system, Southern Alps of New Zealand, Levant fault system. Levant Rift - Red Sea Epeirogeny - Broad warping and vertical movements primary mechanisms responsible for motions in plate interiors. Hot spots and Mantle plumes (Thermal models) Hawaii islands, yellowstone Basin, Saharan Volcanic regions Isostatic Adjustments owing to load removal - Lacustrine evaporation - Lake bonneville Deglaciation - Canadian Shield Denundation - Crustal unloading and formation of escarpments Delamination - Detachment and sinking of lithospheric mantle slabs (episodic uplift of the Colorado plateau) Rift Valleys - East African Rift (Afar Triangle), Rhine Baykal and Rio Grande Rift Failed Rifts - New Madric system in SE USA. Plateaus - Columbia, Colorado, Deccan, Hoggar, Tibet, Parana, Karoo Escarpments - Drakensberg, Western Ghats, Red Sea, Eastern Australia Continental Basins (or intra-cratonic basins) Combination of down warping and uplift of surrounding region. Lake eyre, Chad basin; Kalahari basin; michigan basin Geomorphic systems adjacent to orogenic zones may be thrown into disequilibrium during orogeny, driving forces that cause changes are found in secondary phenomena that are ancillary to the orogenice force. Most priminent are a) Seismicity (earthquakes) - Increases driving force, and New exposed surfaces b) Volcanism Tectonic Geomorphology How tectonic activities affects processes and morphology in geomorph systems and how tectonically controlled landforms can be used to assess Quaternary tectonic activity. 1) Fault-generated landforms in mtns. Fault scarps, offset stream channels; sag ponds and depressions; springs 2) Geomorphic surfaces - Alluvial fans; pediments; marine terraces; fluvial terraces Geomorphic responses 1) Vertical Displacement along faults. Geomorphic response to faulting constitutes one of the basic components in tectonic geomorph a) Mtn front sinuosity b) Ratio between valley floor width and valley height in major river valleys measured at a distance upstream from the mountain. Can see this on page 29 and 31 Kingston Range - Old. Death Valley - Active, Basically: Active is a very sharp scarp with minimal valleys and erosion Inactive is an older, eroded, many valleys where the scarp is jaggedy and goes in and out repeatedly Table 15.1 gives some formulas for determining active/inactive ACRONYMS t = time u = uplift cd = channel downcutting pa piedmon aggradation pd = piedmont degredation Horizontal DIsplacement along faults Examples of landforms found along branch of San Andreas Fault in California. Landforms Associated with Strike Slip faulting. Can Result in wide variety of landforms, including Linear fault through- a valley marking strike-slip fault; occurse by repeated movement and fracturing of rock Sag pond - pond caused by collection of water from springs or runoff into sunken ground resulting from jostling of earth in area of fault movement. -Offset Stream - Offset drainage channel; perhaps most conspicuous landform produced by strike-slip faulting -Shutter Ridge - Displaces Streams flowing across a fault. Pg 32 gives an example of above. Geomorphic Responses 3 3) Tilting/Warping associated w/ broad uplifts. Marine Terraces and Wave-Cut platforms. Longitudinal profiles of river terraces, alluvial valley floors and stream channels River reaches upstream and downstream from uplift axes develop markedly different channel patterns, depths, and sinuosity. Failed Rift is that region in the middle of the US, still moves and has a lot of Earthquakes. Extrusive Igneous Landforms Volcanism - The Surface manifestation of the endogenic processes that create and mobilize magma. How many potentially active volcanoes? ~1500 Basaltic Volcanism - Produced both continental and oceanic environ. Low Si content. Rhyolite/Dacite/Andesite magmas. High Silicic lavas generally restricted to continents or island arcs. HIGH viscosities and greater gas content. Tend to exhibit more violent eruptions. Mt Ararat is one of those ^ Exhalative = Gas, Effusive = Lava, Explosive = Tephra. Pg 39 Figure 5.3 is a good chart. Types of major volcanic landforms: 1) Pleteaus and Tablelands. - Overlapping flows of fluid MAFIC magma, Fissure type eruptions, Comumbia plateau (USA): Deccan Plateau (india) Pahoeahoe/aa/pillow lavas, Silicic Plateaus - Welded Tuffs or Ignimbrites. Lots of wheat in the columbia plateau. Very productive. Grapes, potatoes. 2) Cones. a) Shield volcanoes - Fluid, basaltic magma w/ little tephra. Hawaii and Iceland types. Hawaii and hot spots - Mauna Loa, Mauna Kea b) Composite or Strato-volcano. Cone constructed of interbedded lava flows (mostly rhyodacite and andesite) and tephra (or pyroclastics) - Blocky lavas and steep sopes owing to lack of fluidity of magma (visc) Mt Shasta, Mt Lassen (California). Mt Hood (Oregon), Mt St Helens, Mt Rainier (Washington), Other examples, ararat, fuji C) Cindercone, Conical hill made up primary of tephra (Volcanic ejects such as ash, pumice, and cinders). Can be a source of basaltic lava. D) Domes a) Plug domes and tholoids. Form as result of degassing of rhyolites and andesites. Mono craters result in easten California are plug domes. Small plug domes can also form in strato-volcano craters. b)Maars - small craters produced as result of highly explosive eruptions of gas charged magma metting and reacting with overlying groundwater. -Phreato-magmatic eruption - occurs when groundwater comes into contact with lava or magma. Ubehebe crater in death valley NP Pinnacate Volcanic region Sonora Mexico Harras of Eastern Saudi Arabia. 3)Calderas - Large depression in volcanic regions that result where eruption spews forth large quantities of material, creating an empty space in the underlying magma chamber. This results in inward collapse of the upper part forming the caldera. Largest calderas are associated with volcanoes that produce tephra sheets - Yellowstone Caldera. - Creater lake (explosion of mt Mazama)

22MAR18

Quasi-Equilibrium Every river strives to stablish equilibrium between dominant discharge and sediment load by adjusting hydraulic variables. Channel width and depth Velocity Roughness Water slope Quasi-equilibrium state: Flow variables mutually interdependent meaning that a change in any parameter requires a response in one or more of the otheres. Hydraulic variables. A view of the River Can you summarize what happens with changes in hydraulic variables? Ready up Quasi-Equilibrium: Local optimal energy expenditure hypothesis. Uptimately expressed as 'graded', or equilibrium segments in the longitudinal profile of a river th Also reflected in Channel plan form (ie meandering vs braided) Dynamic equilibrium among inputs into the stream and capacity to move them through. This equilibrium is called the graded stream. It refers to a stream that on average exactly balances its actual sed load to its potential sed load Longitudinal Profile As discharge increases: Channel width increases Channel depth increases Mean velocity is stable Bed material size decreases Slope decreases Sediment storage increases. When and how i fluvial work done? Dominant Discharge - determines characteristics and dimensions of channel Geomorphic work can be estimated in two ways -Amount of Sediment transports for given discharge -Most sed transport occurs rather ordinary discharge that recur at least once every five or ten years. -Conditions under which rivers make adjustments that control or maintain their channel morphos Channel configs related to high freq discharge - BANK FULL DISCHARGE Frequency and magnitude: Recovery Time - TIme needed for river to recover equilibrium form after major flow event Dominant Discharge - Can't have recurrence interval shorter than the recovery time. One flood would not be removed before next channel modifying event. Humid Environments - Recovery time short 1-20yr and controlled by flows of intermediate frequency and magnitude Arid Environments - Longer recovery periods and larger discharges are more important in geomorphic work. Why don't we see more floods? We damed it. Controlled. Basin Sediment Yield page 197? Sediment Yield: Amount of sediment eroded from the basin per unit basin area per unit time Doesn't equal total amount of sediment eroded from upland area. Some sediment is stored in valley bottom. Five factors Climate and veg Basin size Elevation and relief Rock type (Litho) Land use and human activity Dams trap sediment and must be dreged. Land-Use influence on Sediment Yield graph Channel Patterns Braided Meandering Straight Anastomosing Bedload, Mixed Load, Suspended Load. Sinuosity< 1.5 Thalweg: Line of maximum velocity; meanders back and forth between bank. Can be corresponded with deepest part of the river. May develop alternate bars, pools, and riffles. Pools and Riffles: Alternating shallow & wide and deep & narrow Riffles - Hig Velocity, Steep water surface gradient, coarse grained bed materials Pools - Low velocity, gentle water surface gradient, fine grained bed materials Riffle to riffle = 5-7 channel widths Velocity reversal theory: P and R form when Q exceeds threshold such that pool velocity exceeds riffle velocity. Secondary flow patterns: Convergent and Divergent flow Convergent flow in pools facilitates scour Divergent flow in riffles facilitates deposition. GRAPH: Discharge (ft3/s vs Velocity (ft/s) Sequencs of pools and riffles very important. Maintained by scouring (poors) and deposition (Riffles) under high Q Step and pool: Large scale bedform. Boulder and bedrock steps. More than >50% Boulder step: Natural drop structure or fall, formed of boulders the bed as an irregular rib and that separate a backwarer pool upstream from a plunge pool downstream. Log Step: A piece of large woody debris (>0.1m diameter) that spans active channel bed forming natural wooden drop-structure. Important source of energy dissipation. Dune-ripples lowest depositional reach? See graphs that are similar in book. "Cascades, step pools, etc" Meandering channels >1.5 sinuosity, Meandering thalweg, pools, riffles, point bars. Thalweg: Deepest part of a channel that meanders through a river. Erosion where the Thalweg is close and deposition where the THalweg is farthest from channel margin Sites of erosion and deposition that alternate along the channel. Change from straight to meandering: Required sediment transport; helical flow transporting material from meander bend and depositing it in riffle or next point bar downstream. Secondary flow patterns: Spiral and helical Outside of bends - Erosion scouring. Flow accelerates. Inside of bends: Flow decelerating resulting in deposition Pecatonica River near Mineral Point, Wisconsin: Meandering river with ox-bow lakes. Why do rivers meaner: Because they are trying to reach equilibrium. San Juan River- Entrenched Meanders Why have entrenched meander? Gradual uplift over very gentle uplifting and warping. Dead Horse state park. Braided Channels: Wide shallow straight channel with numerous strands of water. Strands divide around coarse-grained bars. Frequent changes in location and number of water strands Total channel width is large compared to channel depth Gradient general steeper than meandering rivers. Easily eroded banks Abundant bed material/bed load Rapid and frequent variations in discharge disallows vegetation to establish on bars. Basically: Too much stuff, Q too weak to move it all (glacial stuff) Anabranching Channels: Relatively permanent multiple sinuous channels w/ cohesive banks. Formation: Avulsion: Local occurance Deposition results in formation of enchannel ridges

15FEB18

Questions such as: How does granite weather. Mechanical vs chemical. Things get into joints and break off. Makes gruss, which goes first. Biotite, Kspar, plag, quarts last. Granite suffers hydrolysis the most. Granite + water + CO2 -> H2CO3 eventually leads to gruss from quartz left over. Major result from the hydrolysis is clays. Secondary minerals. The primary minerals are the qtz, kspar, biotite) Remember Kaolinite is a clay. Clays (kaolinite) + K+ + Silica in solution Know the inselbergs. (Tor, Bernhardt, etc) Sediment yield vs precipitation, he likes that graph. Is it one peak, two peak, three peak? etc Pg44 2.18 A bit of Karsts. There's Hydrolysis and carbonation. Give an example of an above ground and below ground feature. Remember THRESHHOLD CHART. Explain it/draw it. Could be external or internal No questions that aren't on the handouts or that he hasn't covered/talked about. Know the culomb equation and be able to explain about the bits of it and the units. ---------------------------------------------------- Steep slope Gd > Gp moves downslope Moderate Slope Gd = Gp boulder verge of moving Gentle slope Gd < Gp stationary. Partially saturated - weight more evenly distributed, so slightly moist stuff is good, helps with normal load. Slope process: forces primarily reflect weight of material. Specific weight kg/m3 x vertical distance to plane. Controlled by Gravity, shear stress, shear strength Pg 101 describes this well. figure 4.19? Factor of safety: When shear stress <_ shear strength, stable slope -> No mass wasting But Fs > 1 -> Slope stable Fs = i -> stability threshhol When Shear Stress > Shear strength unstable slope => Mass wasting Fs < 1 -> Slope unstable. Pgs 101 to 108 (ft/lb^2) to 1.15 Shear Stress (or force) - the downslope component of gravity tau = gamma h sin(theta)cos(theta) gamma = specific weight sediment (roe g), sin(theta)cos(theta) slope angle. Gravity gravitational force acting straight down related to mass F = mg Shear strength - basically friction; related to material properties and surface the mass is sitting on Rain either increases the load or decreases the strength. (Lowers friction) S = c + sigma tan(fi) Cohesion sigma = effective normal force (gamma H cos^2(theta) fi = internal friction angle due to grain strain contact Normal force - component of gravity that acts perpendicular Shear strength: Resistance to shear force = f (shape, size, sorting, internal fric, normal force, cohesion, pore water pressure) tan(fi) = mechanical resistance offered by friction of grain-grain contact, Plane friction: Grain slides past another Angle of repose: Angle of rest of dry sed, typically 25-40 degrees depending on particle size... Sands around 30 degrees. Angle of sliding friction: Angle at which dry sed fails, up to 10 degrees > angle of repose. Sand -> Coarse sand -> Angular pebbles. Effective normal stress (sigma) Increase ability of sed to hold itself together, loads often increase internal resistance to shear, S increases in dry or moise sed/soil with increases in sigma ' up to some threshhold where pore water pressure becomes positive. Pore water pressure can either strengthen or weaken sediment depending on moisture content dry soil - sigma ' - sigma - 0 moist soi - sigma ' - sigma - (-mu) saturated - Slope materials and water contents: Moderate shear strength dry sand Moist sand highest shear strength; high resistive force Water saturated sand - least shear strength, easily flows. Think sand castle. Calculating internal friction. Linear relationship between shear strength (Y) and shear stress (x) SEE FIGURE 4.22 and 4.20 Cohesive force (c) binding agents salts organic slimes & crusts roots and water unaffected by normal stress (sigma ') an addtnl force due to other factors in rocks: fusion of mins orcementing of grains, eliminating by fractureing In sed: electrostatic forces among fine particles (especially clays) & water clays play a special role in cohesion - with a surface area >> particle volume, clay particles carry a large net negative charge & promote cohesion Atterberg limits: Add water to dry pulverized soil, voids fill and mix becomes increasingly plastic. Further input of water destroys internal fabric to produce fluid Plastic limit (PL): water content at transition from Atterberg limits; determined by soil comp, amount of previous dessication and wetting, and structure W = 0%, pl limit then to another limit Limit controls: Dilatant (rheopectic) strength (visc) up with increasing shear stress Tend to set solid under pressure, typically when rapid stresses cause rearrangement of seds Mudflows in desert environ - water expelled as failure occurs. types of clay mins: Plasticity up w/ % of clay sized particles Wetting drying: Drying brings sed closer together inhibiting further weathering Sensitive soils (Quick clays) Exist w/ water contents over liquid limit, Thixotropic sed (strength) Water can be adsorbed or absorbed by mins in the soil. Adsorption causes electronically polar water molecule to attach itself to the surface of the minerals Absorption causes the minerals to take the water molecules in the structure. Upper clay layers stiff, but lower layers sensitive clay Slide began after 1.5m shaking when lower clay LIQUIFIED clays extruded from toe of slide Sealed off sensitive clay layer. Pull apart basins. Mass Movement Triggers Human induced Undercutting of the base of slope Loading (extra mass) upper part of a slope Increase in momisture content Removal of vegetation Natural: Strong earthquake shaking, explosive volcanic eruptions, torrential rainfall. See TABLE 4.4 Factors that influence stress and resistance in slope materials

08FEB18

Rock Varnish - Often called 'desert varnish' when seen in drylands is paper thin mix of ~2/3rds clay minerals cemented to the host rock typically one-fifth manganese and iron oxyhydroxides --V. IMPORTANT?-- *** Desert Varnish - Nature's smallest sedimentary formation *** Read about this on the internet? http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2451.2011.00813.x/full 3 modes of rock varnish: Physiochemical, Biogeochemical, Other? Clay, but arrives by wind (aeolian source) Only see rock varnish on physically stable rock surfaces that are no longer subject to frequent precipitation, fracting, or wind abrasion. Four ways. Read paper. Figure 24.10 the chart of hyper-arid, arid, semi-arid, humid etc. Growth rate vs Moisture effectiveness. Table 3.4 Common Indices of weathering intensity used t date geomorphic surfaces. Table 3.5 Nomenclature of Soil Horizons. "Note, when you see a Bk horizon, it's a B with Carbonate" Btky clays carbonates and gypsum Arches: Parallel joins undergo weathering and erosion to produce narrow walls of rock that are called fins. Frost wedging and salt weathering causes the xposed rock on each side of the fin to gradually wear away producing exfoliation of arch As weathering continues, exfoliation arch eventually cuts through the fin to produce natural arch Continued weathering causes the hole in the arch to grow larger until arch becomes unstable "Grabben" needles of Canyonlands national park.

18APR18 (LAB)

Smaller basin much better as sediment storage than a large one. Area w/ higher slope more energy so bigger fan But gentler slope less energy in rivers so can't deliver as much sed. Smaller watersheds have steeper slopes. Answer for 11 was looking for the word 'sediment' as requirement for fans. -------- Table 9.2 Morphological, dynamic, and Thermal Classification of Glaciers. Accumulaion: Ice snow water Ablation: Melting calving evaporation sublimation. Peyto Glacier Convert Accumulation to km? Net balance, difference in vs out. So if negative more ablation than accumulation Do it just like #1 1square = 0.5cm (half a centimeter) Scale 1km = 4cm When creating your first plot: You've got zones. Just use the midpoint for your labels and do a down valley profile X axis distance. You will have to mark on zones of accumulation and zones of ablasion. Due by 5pm on Friday.