Geology Chapters 15 & 16
Radial patterns...
Develop where streams radiate outward from an isolated high area
Mass wasting is...
Downslope movement of sediment and rock under the direct influence of gravity
Slump is...
Downward sliding of a mass of rock or unconsolidated material moving as a unit along a curved surface, creating a crescent shape at the head. Occurs on a arched surface
Direction and location of streamflow controlled by primarily geology
Solid bedrock that is a little fractured, and areas of hard rocks interspersed with softer rocks
The angle of repose is...
Steepest angle at which material remains at rest
Meanders are...
Streams with low to moderate gradient, carrying most of its load in suspension, with many curves and bends
A stream is flowing over a hill composed of clay-rich soil. It is eventually blocked to create a small pond in order to free land downhill for construction. What will happen to the strength and cohesion of the soil in the area around this pond?
Strength and cohesion will decrease
What are the three types of loads?
Suspended, Dissolved, and Bed
Rounded gravels prove...
That flat topped features are terraces
Floodplain is...
The flat, broad area surrounding a stream
Triggers for mass wasting are...
Adding water to sediments, over-steepening a slope, or a wildfire
Which sedimentary environment of deposition will be controlled in part by debris flow?
Alluvial fan
The wetted perimeter of stream is...
Amount of flow in contact with the banks and the bed of the channel
Incised meanders...
Are bends in a steep narrow bedrock valley
Zoning regulations...
Are cheap to implement, but can adversely affect property values
Flash floods...
Are local and brief, and very intense. Typically in mountainous regions with impermeable soil
Meanders...
Are sweeping bends of a stream which is migrating laterally in a wide, flat valley
A drainage basin is...
Area where all surface water converges to one location
Deltas are...
At the mouth of a river
Particles moving by saltation are transported into what load?
Bed load, because they jump, skip, and roll at the bottom of the stream
Waterfalls are characteristic of a...
Bedrock channel
Which type of mass wasting involves a crescent shaped scar at the head?
Slump
Floodplain is...
A broad, flat valley floor covered with alluvium characterized by a meandering stream
Formation of meanders...
1) Stream migrates laterally across the floodplain, forming meanders 2) Base level of a stream lowers, and river incises down 3) Incised meanders form 4) Rincon forms by cutoff of an incised meander which shortens the river
Mass wasting causes...
Canyons to widen
At headwaters...
Channel size is smaller, and channel roughness is high
Mouth is...
Characterized by gentle to almost flat terrain, high deposition, low velocity, and high discharge. Depositional
Headwaters is...
Characterized by steep, rugged slopes, high erosion, high velocity, and low discharge. Erosional
Bouncing is to sand as suspension is to...
Clay
Which of the following correctly states the role of rivers and mass wasting in the formation of the Grand Canyon?
Colorado River erodes downward, then mass wasting moves materials from high to low areas, then the Colorado River transports materials downstream
Artificial levees...
Confine water flow and experience significant erosion
Process that causes dissolution of limestone bedrock in a stream is...
Corrosion
Which triggers generated in the 1958 landslide and tsunami at Lituya Bay, Alaska?
Earthquake
What is the continental divide?
Elevational point that divides an entire continent into large drainage basins
Incised meanders and terraces are...
Erosional features
Lakes and streams are...
Examples of local base level
Suspended load is...
Fine grained particles that travel in the water column above the stream bed
A floodplain is...
Flat surface next to a river channel
Rectangular patterns...
Form over highly fractured areas, as fractures typically run perpendicular to each other
Trellis patterns...
Form where streams flow over alternating bands of harder and softer ground, with channels that run parallel to each other
Creep involves...
Gradual downhill movement of soil or rock pieces. Expansion and contraction by freeze and thaw cause this
Which is a major contributor to landslides?
Gravity
Which landslide was caused in part because the underlying sedimentary bedrock was oriented parallel to the slope that failed?
Gros Ventre Landslide (Wyoming). Rather mountainous area
Bed load is...
Highly affected by hte velocity of stream
Solifluction would most likely occur...
In regions underlain by permafrost
Having a narrow, deep channel would...
Increase stream velocity
Sliding is to gravel as dissolution is to...
Ions
Suspended load...
Is affected by both flow velocity and settling velocity of stream
Base level...
Is the lowest level to which a stream can erode
Terrace...
Is the remnant of a former floodplain
Dissolved load...
Is unaffected by velocity of stream
Streams follow the path of_____resistance.
Least
Slide refers to...
Mass movements in which there is a distinct zone of weakness separating the slide material from the more stable underlying material. Movement does not occur on a curved surface. It involves one piece of block
Capacity is...
Maximum load of solid particles a stream can transport per unit in time
Competence is...
Measure of stream's ability to transport particles based on size rather than quantity
Which landscape is prone to generating landslides?
Mountains
Point bars are locations when erosion occurs whereas cutbanks are locations where deposition occurs.
No, false. It is the opposite
Regional floods...
Occur over broad areas and may persist for a long time. Typically in flat areas
Ice Jam floods...
Occur when ice obstructs the flow of water across a channel, effectively damming the stream. As a consequence, the water level rises and overflows its banks
The three zones of a river are...
Of sediment production, sediment transportation, and sediment deposition
Direction and location of streamflow controlled primarily by slope
Peaks surrounded by valleys, solid igneous bedrocks of uniform composition and slope, and layers of solid sedimentary, similar rock
The Great Flood of 1993 in the Upper Mississippi River is what kind of flood?
Regional
Channelization is...
Removing obstructions from a river channel, and may increase bank erosion
Dendritic patterns...
Resemble a branching tree, are most common, and occur over uniform in resistance to erosion
Natural levees are...
Ridges of flood deposits next to a river channel
How can pieces of rock in contact with a stream bed move?
Rolling, sliding, and bouncing
What is part of the bed load?
Sand and gravel
What rock type is the easiest for a river to cut through?
Shale, because it is weak
At mouth...
Slope is lower, discharge is higher
How does the formation of a natural levee impact flooding?
They raise the height of the stream channel, reducing the amount of flooding that will occur on the floodplain
Dams are...
Used to generate hydroelectric power, but are expensive
Graded streams typically have...
V shaped valleys, well-developed floodplains, and meanders
Discharge is...
Volume of H20 flowing past a certain point in a given amount of time
How can water make a slope fail, making a landslide?
Water in pore spaces reduces cohesion between particles, and water makes the slope material heavier
Infiltration is...
Water soaking into the ground
Dam failure floods occur...
When a human made dam or levee breaks
Flow occurs...
When material moves downslope as a viscous fluid
Fall occurs...
When the movement involves the free fall of detached individual pieces of any size, on a very steep slope
Slot canyons are formed...
When vertical incision by a stream is the primary process, with relatively minimal mass wasting
Creep is the most widespread mass wasting process, and it is the slowest
Yes, true
Maximum velocity occurs when the stream is at the bankful stage
Yes, true
Rockfalls are the primary way in which talus slopes are built and maintained
Yes, true
