GEOL 101 Chapter 10
When dry sediment accumulates, the angle of repose represents what property of the deposit?
The steepest angle at which those sediments can accumulate and remain stable.
The Gros Ventre slide is evident today by __________.
a scar, runout area, and landslide debris filling the valley
Which of the following is a reason the Gros Ventre rockslide took place?
Because the river eroded material at the valley base, there was no support of the material upslope.
Which of the following are classifications describing how rock and other material move downslope?
Fall, slide, slump, creep, flow
How is a fall different from a creep?
Falls occur rapidly and in areas with high slope, whereas creep occurs slowly in areas with low slope.
Which type of mass movement event requires the addition of water?
Flow
You will label the five types of mass wasting in terms of the materials they carry. Drag the appropriate labels to their respective targets
-SLUMP MATERIAL: blocks of materials or unconsolidated sediments along a curved surface -SLIDE MATERIAL: blocks of bedrock broken loose and sliding downhill -FLOW MATERIAL: fined-grained materials that can easily flow like a liquid -CREEP MATERIAL: pieces of rock and loose sediments gradually transported downhill; movement of such material is unseen -FALL MATERIAL: boulders on a rocky cliff
Which of the following responses are examples of how water can promote mass wasting? CHOOSE ALL THAT APPLY.
-Waves and streams can undercut banks and cliffs, causing them to fail. -When water is added to weathered particles, the mass of the sediment is increased, which can cause slope instability. -Water can saturate sediment, reducing the integrity of the slope and allowing it to move.
You will explore the differences in mass movement types based on their unique characteristics. Match each key term to the appropriate sentence.
1. A mass movement in which a cohesive block of earth or rock slips downhill relatively quickly in one piece along a zone of weakness is called a SLIDE. 2. Mass movements that move blocks of materials and unconsolidated materials down a curved surface creating scarps on a slope are known as SLUMP. 3. When large rocks become dislodged and drop down a steep slope, the mass movement is called a FALL. 4. CREEPS are very gradual mass movements in which the whole slope moves downhill slowly. 5. When unconsolidated material moves downslope as a viscous fluid it is called a FLOW.
How are debris avalanches and flow related?
Debris avalanches are large, rapid flows of rock.
Describe how a soil particle moves downhill during the freeze-thaw process.
During the freeze, a soil particle moves at a right angle away from the surface, and thawing causes the particle to fall back to a slightly lower level.
When considering mass wasting, which of the following factors is most influential in the downslope movement of weathered particles?
Gravity
What is mass movement?
Movement of material under the influence of gravity alone.
What is used to keep the Trans-Alaska pipeline from melting permafrost?
Stilts
What rock type is the easiest for a river to cut through?
Shale
When sediment accumulates, the angle of repose can be increased by changing which of the following conditions?
Slight addition of water to the sediment
Which of the following is associated with creep?
Slow and subtle movement of material.
How are slumps and slides related?
Slumps are a type of slide in the special case where the rupture surface is curved.
____________ is an example of mass wasting commonly seen in the active layer above permafrost.
Solifluction
Which of the following correctly states the role of rivers and mass wasting in the formation of the Grand Canyon?
The Colorado River erodes downward, then mass-wasting processes move material from high to low areas, then the Colorado River transports material downstream.
What is the name of the near-surface layer that thaws in the summer?
The active layer.
Define mass wasting.
The downslope movement of sediment and rock under the direct influence of gravity.
If permafrost is melted, which of the following is a consequence?
The ground subsides because the volume of water is less than that of ice.
Which of the following statements is true regrading the Gros Ventre rockslide?
The rockslide debris dammed up the river and formed a lake.
What would likely happen to a fence on a hill over time if the fence were built perpendicular to the hill's slope?
The top of the fence would likely bend uphill as creeping rocks moved under the fence and pushed the fence bottom downslope.
Why would trees be J-shaped?
The trunks become tilted in the downhill direction due to creep, but continue to grow toward the sun.
A __________ is a common result of creep.
broken retaining wall
Over time, mass wasting causes ____________.
canyons to widen
A __________ acted as a sliding surface across which material moved downhill during Gros Ventre Slide.
clay layer
Creep is _________.
mass wasting by the gradual downhill movement of sediment, influenced by freeze-thaw or wet-dry cycles
Permafrost is ___________.
permanently frozen ground of tundra and subarctic climates that has remained 0 degree Celsius for two years or more
Heavy rainfall caused the clay to lubricate and the sandstone to become ____________.
saturated and heavy
A ___________ is formed when vertical incision by a stream is the primary process, with relatively minimal mass wasting.
slot canyon