Chapter 11: Mass Wasting

Question 1

Mass Wasting

Answer 1

Gravity movement, either downslope (landslide) or vertical (subsidence)

Question 2

Shear Stress

Answer 2

Component of weight that is directed downslope; increases w/ slope angle

Question 3

Friction

Answer 3

grain to grain contact

Question 4

Angle of repose

Answer 4

the steepest slope angle that dry material will support w/out failing
-related to grain size, shape, and sorting

Question 5

Cohesion(Capillary Force)

Answer 5

Mineral/mineral and mineral/water attraction (electric charge); increases as grain size decreases

Question 6

Water content

Answer 6

• Dry: air in pores (angle of repose); weak
• Moist: air and water in pores; strongest
• Saturated: Only water in pores; weak
• Quick: Only upward-moving water in pores; no strength (liquefaction)

Question 7

Heave

Answer 7

Expansion and contraction of soil’s slope)- slow and small amount

• Wetting/Drying
• Freezing/Thawing
• Heating/Cooling
• Soil Creep
• Talus Creep

Question 8

Slide

Answer 8

Moves as a unit; no internal deformation

• Slip-translation
• Slump-rotation
• Landslide, rockslide

Question 9

Flow

Answer 9

Internally deformed

• grain flow; dry sand
• mudflow; debris flow, lahar
• debris avalanche
• solifluction (common in saturated active layer above impermeable permafrost, can be quick)

Question 10

Fall

Answer 10

Free fall from cliff; rock fall

Question 11

Subsidence

Answer 11

Vertically downward movement, gradually (sinking) or suddenly (collapse)

Question 12

Compaction

Answer 12

Gradual sinking

• compressible materials (Mississippi River Delta)
• Underground fluid w/drawl (San Joaquin Valley; ground water removal)

Question 13

Collapse

Answer 13

Due to large, subsurface holes

• Limestone caves: sinkholes, karst topography
• Underground mines

Question 14

Karst Topography

Answer 14

Lanscape consisting of numerous caves, sinkholes, and solution valleys formed by groundwater solution of rocks such as limestone and dolostone