EV203 Quiz 3

Porosity

The percentage of the total volume of a rock or sediment that consists of open spaces (pore spaces or cracks) that can be filled with water

Badlands

Wasteland that has been carved into unusual shapes by wind and water. the intricately dissected and barren terrain, a type of dry terrain where softer sedimentary rocks and clay-rich soils have been extensively eroded by wind and water. They are characterized by steep slopes, minimal vegetation, lack of a substantial regolith, and high drainage density.

silt

fine soil found on river bottoms

competence

largest particle a stream can carry (dependent on flow velocity).

List and describe the five soil-forming factors (geologic, climatic, topographic, biological, and time). Explain how they contribute to the development of soils.

1) Geologic (parent material: either bedrock or loose sediments transported by water, ice, or wind. Chemical and physical composition of parent material influences soil development, specifically in terms of texture and structure) Initial forming materials for soil, this is what weathers and gives rise to soils 2) Climate (i.e. in warm humid A regions, more precipitation = more soil formation) temperature and moisture = greatest significance to soil formation. (wet and hot=ideal conditions for weathering, hot and dry not as ideal) red clays=ferric oxide. 3) Topography (i.e. soil layer deeper in valley/flatlands as opposed to mountains) Slope and drainage. rolling hills vs gently flat slope. Gravity always wins, causing erosion on hillsides. Hilly areas have thin soil vs flat areas have deep soil. 4) Biologic (i.e. effects of worms, root systems) (fauna and flora): grass roots of prairie experience lifecycle (continual deposition of the form of organic matter). Organisms matter! 5) Time (most soil development takes place on scales of time longer than human life expands.) in wisconsin, glaciers scraped soil off of bedrock. If happened 15,000 years ago, soil only forming for 15,000 years vs soils forming for millions of years.

Soil

A relativly thin surface layer made up of a mixture of mineral particles and organic material that covers the land, and in which terrestrial plants grow.

Permeability

Ability of rock or soil to allow water to flow through it. the ability to transmit underground water; this property of subsurface matter is determined by the size of pores and by their degree of interconnectedness. The smaller and less connected the pore spaces, the less permeablie the material and the slower the water moves.

Describe the two categories of aeolian erosion (deflation and abrasion) and how they create blowouts and ventifacts. Explain how rock material is moved through aeolian transportation processes.

Aeolian processes are effective wherever fine-grained unconsolidated sedimentary material is exposed to the atmosphere without protection. Aeolian erosion: Deflation: shifting of loose particles as a result of being blown through the air or along the ground. Creates blowout, a shallow depression from which an abundance of fine material has been deflated. Abrasion: requires airborne sand and dust particles to drive against rock and soil surfaces in a form of natural sandblasting. Creates ventifacts, rocks faceted by such wind The wind-caused etching or pitting of rock surfaces is termed ___abrasion_____. Aeolian Transportation: Suspension Saltation and traction Aeolian transportation: Saltation: most sand leaps along the surface from strong winds, striking the ground and bouncing onward. Traction: how larger articles move, being rolled or pushed along the ground by wind.

Describe the Pleistocene glaciation, the extent of the glaciation, the resulting sea level changes, and the associated crustal depressions.

An alteration of glacial periods and interglacial periods (times of ice accumulation vs times of ice retreat). Moving ice grinds away anything in its path: most soil is carried away, and bedrock is polished, scraped, gouged, plucked, and abraded. The rock that is picked up is deposited in new locations. Extent: Ice covered ⅓ of the total land of the earth at its max. Ice thickness varied but in certain areas reached thousands of meters At its maximum extent, continental glacial ice in North America extended as far south as ___the Ohio River_____. During the Pleistocene, the ___Laurentide_____ ice was the most extensive continental ice sheet in the world. Sea Level Changes: when continents were covered with ice, less water was available to drain from the continents into the oceans, resulting in worldwide sea-level lowering. Sea level rises again as meltwater returns to oceans. Crustal Depression: Enormous weight of ice caused portions of Earth's crust to sink by as much as 12000 meters. When ice melted, crust slowly began to rebound and is still rebounding today in certain areas.

Identify and describe the landforms created by continental ice sheets and mountain glaciers. Explain how they are formed. In particular, explain how roche moutonées and moraines (terminal and recessional) are formed by continental ice sheets. Explain how glacial troughs, hanging glacial troughs, and moraines (lateral and medial) are formed by mountain glaciers.

Continental ice sheets smooth and round the terrain while mountain glaciations tend to steepen slopes and increase local relief Continental Ice sheets: Topography resulting from the erosion is a gently undulating surface. Roche moutonnee: (caused by both glaciers) one side is smoothly rounded but the other side is shaped by plucking, which produces a steeper and more irregular slope. May cause a veneer of unsorted debris, producing an irregularly undulating surface of broad, low rises and shallow depressions (till plain). Moraines: glacier deposited landforms composed entirely or largely of till. Terminal: ridge of till that marks the maximum advance of a glacier. Forms when a glacier reaches its equilibrium point (wasting at the same rate it is being nourished). Pieces of rock are transported to the front of a glacier as ice within the glacier moves. Recessional: may develop as the glacier recedes. These are ridges that mark positions where the ice front was temporarily stabilized during the final retreat of the glacier. Mountain glaciers Do not usually reshape terrain as completely as continental ice sheets. Cirques: a broad amphitheater hollowed out at the upper most head of a glacial valley; has a steep, perpendicular head and side walls and a flat or gently sloped floor that may form a basin; marks the place where an alpine glacier originated. Aretes and Cols, Horns Glacial Troughs, glacial steps, hanging glacial troughs, lateral moraines Glacial Troughs: long, U-shaped valleys that were carved out by glaciers that have since receded or disappeared. Troughs tend to have flat valley floors and steep, straight sides. Forms as glacier moves down valley with great erosive force. Hanging Glacial Trough: Hanging valleys are typically formed when the main valley has been widened and deepened by glacial erosion, leaving the side valley cut off abruptly from the main valley below. The steep drop from the hanging valley to the main valley floor usually creates cascading waterfalls. Lateral Moraine: well defined ridges of till built up along the sides of valley glaciers. Medial Moraine: the dark band of rocky debris that continues where a tributary glacier joins a main valley glacier and unites their lateral moraines at the intersection.

Explain how glaciers shape topography through erosion (glacial plucking and glacial abrasion); transportation; and deposition (direct deposition and secondary deposition by meltwater).

Erosion: proportional to the thickness of the ice and its rate of flow. Glacial plucking: As the moving ice scrapes against bedrock, friction causes the lowermost ice to melt, and the water created reduces pressure on the rock. This can refreeze and can exert significant force as it is pushed by the ice behind it. Rock fragments are grasped as water freezes in joints and fractures where frost wedging occurs. As the ice moves, the particles are plucked out and dragged along; tends to roughen underlying surfaces. Abrasion: bedrock is worn down by rock debris dragged along in the moving ice; produces polished surfaces and grooves. Transportation: most material is plucked or abraded and is carried along at the base of the ice. Some material transported on top of the ice, deposited by rockfall or other forms of mass wasting from the surrounding slopes. Rockflour: part of a glacier's load Melt streams: streams of meltwater flow along with the moving ice. Deposition: The general term for all material moved by glaciers is drift. Direct deposition: rock debris deposited directly by moving or melting ice with no meltwater is called till; the result is an unsorted and unstratified agglomeration of fragmented rock. Secondary deposition: glacial stream runoff carries debris directly from the ice and carries sedimentary material washed form positions in, on, or beneath the glacier.

Identify, name, and describe the geomorphic features associated with surface water in deserts (exotic streams, ephemeral streams, playas, and saline lakes).

Exotic Streams: permanent streams in dry lands sustained by water that originates outside the desert. Ephemeral Streams: streams which carry water seasonally or after a rainstorm. Brief periods of flow are times of intense erosion. Playas: dry lake beds, among the flattest and most level of all landforms Saline Lakes: an example of a permanent lake in a desert area where high rates of evaporation relative to the inflow and or basins of interior drainage lead to the accumulation of dissolved salts Exotic stream: sustained water that originates outside the desert; water comes from an adjacent wetter area or a higher mountain area in the desert and has a sufficient volume to survive passage across the dry lands. Ephemeral stream: seasonal streams; flow only during and immediately after a rain; flow during times of intense erosion, transportation, and deposition. Playa/saline lake: dry lake beds; the term salina may be used if there is an unusually heavy concentration of salt in the lake-bed sediments; playa lakes occur when intermittent streams have sufficient flow to bring water to the playa; playas are the flattest and most level landforms. Many permanent lakes in desert areas are saline lakes - high rates of evaporation relative to the inflow and/or basins of interior drainage lead to the accumulation of dissolved salts in such lake waters.

Describe how floods are agents of erosion and deposition. Explain how recurrence intervals are used to describe the probability of a flood event. Describe how flood controls are implemented.

Flood Controls; Dams, Artificial Levees, Outwash areas Recurrence Intervals: how often you expect to see a flood within certain time period.

Identify, name, and describe the landforms commonly associated with floodplains (floodplains, bluffs, cutoff meanders/ oxbow lakes, natural levees, backswamps, and yazoo streams). Explain how each forms.

Floodplains: a. low-lying, nearly flat alluvial valley floor that is periodically inundated with floodwaters; formed when meandering stream flows across wide, nearly flat valley floor; may produce rapid and sometimes abrupt changes in the channel. b. Shifting of stream meanders produce increasingly broader, flattish valley floor largely or completely covered with deposits of alluvium left by periodic floods Bluff: the outer edges of a floodplain usually bounded by an increase in slope. Marking the outer limit of lateral erosion and undercutting flat terrain. Cutoff Meanders: often a meander loop is bypassed as the stream channel shifts by lateral erosion and cuts a new channel across its neck, leaving the old meander loop Oxbox lake: cutoff meander filled with water for a period of time Meander Scar- when oxbow lake dries out Natural Levees: A floodplain is slightly higher along the banks of a stream channel than anywhere else. As the stream overflows during a flood, friction with the floodplain surface slows the current when it leaves its normal channel; when deposition takes place along the margins of the main channel. Backswamps: natural levees merge outwards and almost imperceptibly with the less-drained, lower portions of the floodplain, known as backswamps. Yazoo Stream: when a tributary system entering a floodplain cannot flow directly into the main channel because it encounters prominent natural levees, it instead flows downvalley into the backswamp zone, running parallel to the main stream for some distance before finding an entrance.

Explain how glaciers form. Explain the balance between glacial accumulation and ablation and how this relates to glacier flow, glacier advance, and glacier retreat.

Glacier develops when there is a net year to year accumulation of snow. After many years of accumulation, the ice mass begins to move under the pull of gravity, forming a glacier. The persistence of any glacier depends on the balance between accumulation (addition of ice by incorporation of snow) and ablation (wastage of ice through melting and sublimation). When a mass of ice attains a thickness of 50 meters, there is an oozing outward from around the edge of an ice sheet or downvalley from the toe (the end) of an alpine glacier). Basal slip at the bottom of the glacier occurs when the entire mass slides over its bed on a lubricating film of water. Glaciers move slowly and at different rates. The fastest ice is at and near the surface, and speed generally decreases with depth. If the glacier is confined, the center moves faster than the sides. The ice in a glacier always moves forward, but the outer margin of the glacier may or may not be advancing, depending on the balance between accumulation and ablation. During wetter or cooler periods (increased accumulation), a glacier can flow farther before it wastes away, so the outer margin of the glacier advances. During warmer or drier periods (increased ablation), glacier continues to flow but wastes away sooner, so the end or terminus of the glacier retreats. Retreating glacier: outer margin is retracting toward its point of origin due to heavy ablation) and ice still flows forward.

Identify, diagram, and describe the component parts of a groundwater system, including aquifers, aquicludes, the zone of aeration, the zone of saturation, the water table, cones of depression, confined aquifers, artesian wells, and the waterless zone.

Groundwater is underground water in the subsurface zone where the pore spaces are completely filled with water (the zone of saturation), but the term often refers to all underground water. Aquifers: underground water is stored in, and moves slowly through, moderately to highly permeability rocks called aquifers. Aquicludes: Impermeable materials composed of components such as clay or very dense unfractured rock which hinders or prevents water movement The Zone of Aeration: the topmost band, a mix of solids, water, and air. The interstices are filled with water and air where amount of water fluctuates with time. The Zone of Saturation: below zone of aeration where all pore spaces in soil and cracks in the rocks are filled with water. Groundwater seeps slowly through the ground following the pull of gravity and guided by the rock structure. The Water Table: the top of the saturated zone. Orientation and slope usually conforms to the slope of the land surface above. Cones of Depression: A well dug into a zone of saturation fills with water up to the level of the water table. When water is taken from the well faster than it can flow in from the saturated rock, the water table drops in the immediate vicinity of the well in the approximate shape of an inverted cone. If many wells withdraw water faster than it is replenished, the water table may be significantly depressed over a large area, causing shallow wells to go dry. Confined Aquifer: aquifers in the zone of saturation confined by aquicludes above and below. Water cannot penetrate from direct infiltration Artesian Wells: when a well is drilled from the surface down into the confined aquifer, the pressure forces water to rise in the well. When pressure is enough to allow water to rise above the ground, it causes a free flow of water. Waterless Zone: the lower limit of the zone of saturation which lacks pore spaces and thus water. The rock here cannot hold or transmit water.

Groundwater

Groundwater refers to all the water flowing underground. Groundwater flow pattern is determined by the force of gravity. In response to gravity, water moves from areas where the water table is high to zones where the water table is lower. Although some water takes the most direct path down the slope of the water table, much of the water follows long, curving paths. The deeper you go into the saturation zone, the greater the water pressure. As a result, water at any given height is under more pressure beneath a hill than beneath a stream channel and water tends to move laterally from the higher pressure zones to zones of low pressure.

Name and describe common hydrothermal features (hot springs, geysers, and fumaroles).

Hot Spring: underground water has come in contact with heated rocks or magma and has been forced upward through a fissure by the pressures that develop when water is heated. Results in water bubbling Geyser: a special form of intermittent hot spring, where hot water tends to spew sporadically and most of all flow is only a temporary ejection (eruption) in which hot water and steam spout upward. The geyser then subsides into apparent inactivity until the next eruption Occurs when groundwater seeps into subterranean openings that are connected in a series of narrow caverns and shafts. Heated rocks or magma is close enough to provide a constant source of heart, heating water in the upper chambers where pressure is lower, causing water to expand and burst out. Fumaroles: a surface crack that is directly connected to a deep seated heat source. Like a geyser except it erupts steam instead liquid water.

Describe the two primary types of glaciers (mountain glaciers and continental ice sheets).

Ice must be flowing or moving to be considered a glacier. Mountain glaciers: in high-mountain areas, ice accumulates in an unconfined sheet, submerging all underlying topography. Their outlets are often tongues of ice that travel down valleys in the mountains. If the leading edge of a valley glacier reaches a flat area and escapes from the confines of a valley, it is called a piedmont glacier. In the Himalayas, Montana, Yosemite, found in mountains Continental Ice Sheets: glaciers that form in non-mountainous areas; vast blankets of ice that completely inundate underlying terrain; the ice accumulates to great depths in the interior of the sheet but is much thinner at the outer edges. Antarctica, Greenland. Bigger than mountain glaciers

Name and describe the types of landforms commonly associated with karst topography (caverns, speleothems, sinkholes, surface drainage, and haystack hills/mogotes). Explain how each forms.

Karst = topography developed as a consequence of subsurface solution; special landform that develop on exceptionally soluble rocks. Rolling, rounded hills with numerous depressions Caverns formed from dissolution along joints and bedding planes in limestone beneath the surface, often creating large areas Speleothems formed when water leaves behind compounds it was carrying in solution. Once out of solution, carbon dioxide gas diffuses into the cave atmosphere and calcite is deposited. Stalactite: precipitation drips from roof forming icicles Stalagmite: wen drip hits the floor, icicle grows upward Sinkholes: rounded depressions formed by the dissolution of surface carbonate rock, typically at joint intersections. Sinkholes erode more quickly than surrounding area, forming closed depressions. Surface Drainage: where sinkholes occur in profusion, often channel runoff into the groundwater circulation, leaving networks of dry valleys as relict surface forms. Lack of surface drainage; disappearing streams Tower Karst (haystack hills/mogotes): residual karst features in the form of very steep sided hills, where high rainfall occurs and dissolves area around the base of the hill.

Explain how valleys widen through lateral erosion.

Lateral erosion by a meandering stream. Valley Widening: downcutting diminishes with time as gradient is reduced; stream's energy diverts into meandering flow patterns i. As the stream sways from side to side, lateral erosion begins and widens the valley floor. ii. Water moves fastest on the outside of curves (cut bank) and there it undercuts the bank. iii. On inside of the curve where water moves slowly, alluvium accumulates, forming a point bar.

Predict the type of soil found in a location based on its dominant soil-forming factors.

Look at factors then look at soil order. Look at Goode's World Atlas Factors Climate: Biological Topographic Geographic Geologic Time

Identify, name, and describe the landforms associated with basin-and-range regions (ranges, alluvial fans, bajadas, and basins). Explain how these geomorphic features are formed. Locate the basin-and-range regions of North America.

Most of the southwestern interior of the United States is characterized by basin-and-range topography A land largely without external drainage with only a few exotic rivers. Has undergone extensive normal faulting. Ranges: long, narrow, and parallel to one another. Their surface features have largely been shaped by weathering, mass wasting, and fluvial processes. Alluvial Fans: a fan- or cone-shaped deposit of sediment crossed and built up by streams. If a fan is built up by debris flows it is properly called a debris cone or colluvial fan. These flows come from a single point source at the apex of the fan, and over time move to occupy many positions on the fan surface. A semi-circular to conical accumulation of coarse-grained sediments. Formed when Stream gradients decrease at the mountain front, causing deposition characteristic of the basin-and-range region; as a flowing stream leaves the narrow confines of a mountain gorge and emerges onto the open piedmont zone, it slows down and abruptly loses capacity and competence. The flow breaks into channels that deposit sediment that extend outward across the piedmont zone and onto the basin floor creating a fan. Bajada: a continuous alluvial surface all across the piedmont zone, making it difficult to distinguish between individual fans. Basins: the flattish floor which very gently slopes from all sides toward some low point. A playa is usually found here.

Identify, name, and describe the landforms associated with mesa-and-scarp terrain (plateaus, mesas, buttes, and pinnacles). Explain how these geomorphic features are formed. Locate the mesa-and-scarp regions of North America.

Most prominent in four corners zone. Mesa=flat-top surface, Scarp=steep, more or less vertical cliffs Plateau: the top platforms bounded on one or more sides by a prominent escarpment Mesa: flat-topped, steep sided hill with a limited summit area Butte: an erosional remnant that has a very small surface area and cliffs that rise inconspicuously above their surroundings Pinnacle: with further denudation, a pillar shape is left, a final spire of resistant caprock protecting weaker underlying beds. Great vertical escarpments are associated with ___differential erosion_____ of sedimentary strata in desert climates.

Aeolian processes

Processes related to wind action that are most pronounced, widespread, and effective in dry lands. pertain to wind activity in the study of geology and weather and specifically to the wind's ability to shape the surface of the Earth

Identify and name the types of sand dunes created by aeolian deposition. Explain how sand dunes are formed.

Sand Dune: loose, sand blown sand is piled into a mound or low hill Barchan: occurs as an individual dune migrating across a non sandy surface (although sometimes found in groups). Fastest moving and found in almost all deserts (except australia). Formed by constant strong winds and move in very dry deserts. Transverse: less uniformly crescent shaped than barchans, occur where normally the entire landscape is sand covered. Perpendicular to wind Seifs: a type of linear or longitudinal dune. Long, narrow, dunes that usually occur in abundance and in a generally parallel arrangement. Parallel to wind Star Dunes: large pyramid shaped dunes with arms radiating out in three or more directions. Formed by wind variation in different direction.

Classify the following major soil orders based on their dominant development pathways (site-dominated, climate-dominated, or parent material-dominated): histosols, gelisols, mollisols, aridisols, oxisols, vertisols, and andisols.

Site Dominated Pathway: Histosols: "tissue", wet, swamp. Lots of moisture but no air. Have all the organic material but no oxygen to respire. Leads to build up of organic material which leads way to deep organic soils. Louisiana, florida, any swampy area. Parent Material Dominated Pathway: Andisol: volcanic, the andes mountains are volcanoes. US pacific northwest, hawaii, aleutian islands, the ring of fire, the andes, iceland, wherever we find volcanoes. andesite, rock formed from type of magma in Andes mountains volcanoes, soils high in volcanic ash. Parent material dominated pathway; clayey materials, wet-dry climate. Vertisols: high activity clays. 2 tetrahedral sheets per 1 octahedral sheet, meaning they are able to shrink and swell with addition/removal of water. Smectite = expanding, most swelling. Texas!!!!!! No basements because when rain comes, dirt swells and basement cracks, reverse occurs too. No good pattern for across the pattern, geological oddity (india, east africa, australia). Latin verto "turn", soils in which the usual horizon order is inverted. Parent material dominated pathway; volcanic materials Climate Dominated Pathway: Gelisol: frozen material, cryoturbation. Cold areas, alaska, northern regions of world, himalayas: altitude leads to decrease in temp Mollisols: soft, prairie material, sufficient precipitation for grasses but not trees. Midwest: great plains, campus. RAINSHADOW. More rain after we get through rainshadow. Fond in breadbaskets of world, extremly fertile. Aridisols: dry: Lack of precipitation leads to lack of weathering. Desert southwest. Subtropical high=not alot of rain Oxisols: Oxygen, soils rich in oxygen containing compounds. Time-dominated pathways (between parent and climate); extremely old soils, hot, humid climate. Vegetation in areas with oxisols is often lush and diverse tropical rain forest, with a very robust organic horizon. Slash-and-burn shifting agriculture was adapted to oxisols. As a result of warm temperatures, high humidity, and high amounts of precipitation, organic material can decay into soil as much as seven times faster than in other environments. However, this "O horizon" requires constant input and can quickly decrease in fertility. After several years of economic use, people shift agriculture to another tract of land.

List, identify, and describe each of the four stream channel patterns (straight, sinuous, meandering, and braided). Describe the conditions under which each is most likely to occur.

Straight · Often very short · Uncommon Short sections of a channel Eventually take on sinuous characteristics due to scouring and filling Sinuous · Winding channel · Usually high gradient · Mountain valleys or other relatively uniform geographic structure · Faster water than meandering but not as curving · Not as curvy as meandering Common Steep gradients (generally) Fairly fast NOT curvy, fairly straight Meandering · Serpentine · Low gradient, flat land · Continuous process of deposition and erosion · Most rock transported are fine-grained suspended load · Fastest part of water on outsides (creating cutbanks); slowest water on inside curves (deposits onto point bar) Tightly curved loops Abandoned channels Where land is flat, such as large floodplains Ex: mississippi River Braided · Multiplicity of interwoven and interconnected channels separated by low bars or islands of sand, gravel, and other loose debris · Takes place when very flat stream channel has heavy load of sediment and in regions with prominent dry seasons and period of low stream discharge · Commonly found in · Alpine regions (spring snow melt) and when glaciers melt · Arid areas (fast convective storms, monsoons) · Rivers flooding Relatively gradual land Abundance of sediment Heavily loaded stream Gentle gradient slows flow speed Slow moving stream chokes channel with alluvium Sand and gravel bar deposits divide (braid) the stream Inconsistent stream flow

Explain the concepts of stream erosion, transportation, and deposition. Describe the three components of stream load (dissolved load, suspended load, and bed load).

Stream erosion: detachment and removal of fragmented and weathered rock material through the hydraulic power of the moving water Transportation: Both overland and stream flow can transport rock material i. Stream load: solid matter carried by a stream. 1. Dissolved load: minerals, mostly salts. 2. Suspended load: fine particles of silts and clays 3. Bedload: larger fragments of sand or gravel a. Saltation: small particles bounce along the bottom b. Traction: coarser particles roll or slide along the bottom ii. Competence: largest particle a stream can carry (dependent on flow velocity). iii. Capacity: amount of solid material a stream has the potential to transport (dependent on flow velocity and volume) Deposition: the placement of material that has been moved from another location. i. Usually ultimate destination either ocean, lake, interior drainage basin ii. Alluvium: stream deposited sediment. iii. Stream deposition occurs when there is a decrease in velocity causing a decrease in competence and capacity Fluvial Erosion: Erosion by streamflow Volume of flow Abrasion of streambed Chemical weathering of channel Turbulence of flow Flow speed Rocks smoothed out and rounded Water sorts things very well Deposition Alluvium sorted/stratified deposits Smooth, rounded particeles cause : decrease in flow speed Steamflow variability Fluvial Transport Mechanisms: (FRAME ALL ANSWERS IN TERMS OF COMPETENCE AND CAPACITY) Stream load: the solid matter carried by a stream Types of load: dissolved, suspended, bedload Competence (the largest size particle river can carry, dictated by velocity/speed) Capacity (amount of materials river can carry, dictated by speed/velocity and volume of water)

Explain how fluvial erosion influences the landscapes of arid lands. Describe the flash flood hazards associated with arid lands. Explain how differential weathering influences the development of landforms in deserts.

The lightly vegetated ground is defenseless to rainfall, and erosion by rain splash, sheetwash, rilling, and stream flow are very effective. Fluvial erosion works rapidly and effectively. During rare rains, bedrock is mechanically weathered and eroded by running water, and the result is steep, rugged, rocky surfaces. Flash flood hazards: arrive without warning Differential erosion: produces differences in the slope and shape of the resulting landform; common in sedimentary landscapes because there are significant differences in resistance between stratum.

Till

The sediments deposited directly by a glacier

Groundwater Questions

Underground water is a weak carbonic acid The primary way in which underground water shapes topography is through chemical action Karst ________ is the term for solution topography in regions of limestone bedrock. Karst landscapes are noteworthy because __surface streams______ are usually absent.

Explain how valleys deepen through downcutting and knickpoint migration.

Valley Deepening: downcutting is dominant activity whenever stream has relatively rapid speed or relatively large volume i. Base level = lower limit to how much downcutting a stream can do ii. Produces deep valleys with steep sides and V-shaped cross section iii. Knickpoint migration: valley shape develops first in lower reaches then progressively proceeds upstream A ___knickpoint_____ develops along a streambed containing bedrock of differential resistance Valley Deepening Downcutting and V-shaped valleys Head (upper end) of a valley Downcut until you hit Base level Knickpoint Migration Erosion of softer underlying layer pushes back waterfall Niagara Falls keeps moving

Explain how valleys lengthen through headward erosion, stream capture, and delta formation.

Valley Lengthening: i. Headway erosion: erosion that cuts into the interfluve at the upper end of a gully or valley ii. Delta Formation: lengthened at seaward end because of deposition; flowing water slows down and deposits load which creates a delta. This partially blocks the channel and forces stream to seek new path. River mouth deposits (into a still body of water) When hits ocean, competence and capacity decrease as velocity decreases, causing sediment to pile up. Water flows to path of least resistance, so as deposit piles up, switches direction (constantly changing with time). Dams cause loss of sediment which leads to loss of land Iii. Stream Capture: dramatic headward erosion when a portion of the drainage basin of one stream is diverted into the basin of another stream by natural processes

Permeability and Porosity

Water can only be present underground in areas where rocks have porosity—spaces or voids within the rock material. Well-rounded coarse-grained sediments usually have higher porosity. For water to move underground, rocks need to have permeability, or connections between pore spaces.

Explain the process of groundwater mining and describe the problems associated with it.

Water is accumulated in the ground very slowly, however, it is pumped out at a far greater rate. Aquifers are discovered and tapped, idea of fossil water. In addition to depleting the water supply, mining causes subsidence of the surface, casing land to sink rapidly. Humans cause the water table to lower, so sinkholes increase. Wells dug into the zone of saturation fill with water up to the level of the water table. When water is taken from the well faster than it can be replenished, a cone of depression forms. If many wells are withdrawing water too fast, the water table may be lower over a large area, causing shallower wells to dry. In addition to depleting the water supply, groundwater mining causes the compaction of sediments which leads to subsidence of the surface.

horizon

a layer of soil. s a layer parallel to the soil surface, whose physical characteristics differ from the layers above and beneath. Each soil type usually has three or four horizons. Horizons are defined in most cases by obvious physical features, mainly colour and texture.

Explain the processes of dissolution and precipitation. Describe how these processes result in caverns and related features.

a. Dissolution: removal of bedrock through chemical weathering and action of water i. particularly effective on carbonate sedimentary rocks (limestone) ii. Erosion occurs more rapidly in humid climates iii. Profusion of joints and bedding planes permits groundwater to penetrate rock readily b. Precipitation: complementing the removal of calcium carbonate is its chemical precipitation of solution back into solid form. Mineral-rich water can trickle back in along a cave or wall, where reduced air pressure in the open cave then induces precipitation of the minerals the water is carrying. Caverns formed from dissolution along joints and bedding planes in limestone beneath the surface, often creating large areas Speleothems formed when water leaves behind compounds it was carrying in solution. Once out of solution, carbon dioxide gas diffuses into the cave atmosphere and calcite is deposited. Stalactite: precipitation drips from roof forming icicles Stalagmite: wen drip hits the floor, icicle grows upward

capacity

amount of solid material a stream has the potential to transport (dependent on flow velocity and volume)

organic matter

any substance that is made of living things or the remains of living things

point bar

deposit of sediment build up by a river on the inside bend of a meander. caused by deposition of alluvium on the inside of bends

Glacial erratics

enormous boulders transported and deposited by glaciers, often far from their source region

cut bank

the area of active erosion on the outside of a meander erosion occurs on the outside of the meander bend where the water flow is fastest, forming the cut bank.

clay

the finest soil, made up of particles that are less than 0.002 mm in diameter.

hydrologic cycle

the movement of water through the biosphere. The water cycle, also known as the hydrological cycle or the hydrologic cycle, describes the continuous movement of water on, above and below the surface of the Earth. Wikipedia

differential weathering

the process by which softer, less weather resistant rocks wear away and leave harder, more weather resistant rocks behind

parent material

the rock material from which the inorganic components of a soil are derived

Describe the components and properties of soils.

· Soil = mixture of weathered mineral particles, decaying organic material, living organisms, gas, liquid solutions · Regolith = an inorganic layer of broken and partially decomposed rock particles (fragmented rock) · Bedrock = solid rock under regolith Components: Inorganics: bulk of most soils is mineral matter Organic Matter: constitutes less than 5% but has enormous influence on soil characteristics and plays a fundamental role in the biomechanical process that makes soil an effective medium of growth (litter=dead plant parts accumulated at surface. Humus: "black gold" that is of utmost importance to agriculture.) Air: half the volume of soil made up of pore spaces providing a pathway of interconnecting passages (interstices) for air and water among the soil particles. Water: gravitational water, capillary water (water of cohesion: attraction of water molecules to each other), Hygroscopic water (water of adhesion: attraction of water molecules to surfaces), combined water Properties: Color Texture (size groups called separates) Structure (peds: individual particles tend to aggregate into clumps)