Chapter 15 Mass Wasting: The Work Of Gravity

Front 1

angle of repose

Back 1

This is the steepest angle at which unconsolidated material remains stable

Front 2

debris flow (mudflow)

Back 2

a rapid type of mass wasting that involves the flow of soil and rock debris containing a large amount of water

Front 3

lahars

Back 3

unstable mudflows that are generated at the base of a volcano often carries large debris (even cars and large boulders)

Front 4

Earthflow

Back 4

The downslope movement of water saturated, clay rich sediment. (occurs in humid environment) very slow fluid movement (small)

Front 5

Creep

Back 5

Involves extremely slow downslope movement of soil or weathered debris (regolith) (It causes telephone pole and trees to curve)

Front 6

Name one factor that contributes to creep

Back 6

alternating contraction and expansion caused by freezing and thawing or wetting and drying of material

Front 7

solifluction

Back 7

A slow downslope flow of water-saturated materials common to permafrost areas

Front 8

permafrost

Back 8

Any permanently frozen sub-soil

Front 9

active layer

Back 9

The zone above the permafrost layer that thaws in the summer and refreezes in the winter

Front 10

During the summer the active layer is unable to percolate into the permafrost layer and what happens in a result

Back 10

The active layer becomes saturated and slowly flows known as soliflution

Front 11

Slump

Back 11

The downward slipping of a mass of rock or unconsolidated material moving as a unit along a curved surface.

Front 12

The rapid slide of a mass of rock downslope, along planes of weakness.

Back 12

slide

Front 13

What is the fastest and most destructive mass movement

Back 13

Rockslide

Front 14

Name the 4 types of mass movement

Back 14

slides (rock slides), Slump, debris flow, and earthflow

Front 15

What are the 5 factors that cause mass wasting

Back 15

water, gravity, overstepped slopes, earthquakes, and the removal of vegetation

Front 16

When considering mass wasting, which of the following factors is most influential in the downslope movement of weathered particles?

Back 16

Gravity

Front 17

name 3 ways how water can promote mass wasting?

Back 17

1)Waves and streams can undercut banks and cliffs, causing them to fail.

2)When water is added to weathered particles, the mass of the sediment is increased, which can cause slope instability.

3)Water can saturate sediment, reducing the integrity of the slope and allowing it to move.

Front 18

When sediment accumulates, the angle of repose can be increased by changing what following condition?

Back 18

slight addition of water to the sediment

Front 19

When a slurry of unconsolidated material moves downhill it is called a

Back 19

flow

Front 20

_________ very gradual mass movement that causes the entire slope to move downhill slowly

Back 20

Creep

Front 21

when large rocks become dislodged and drop down a steep slope, the mass movement is called

Back 21

fall

Front 22

Mass movement that causes material to move along a curved surface and creating scarps on the slope are known as

Back 22

slump

Front 23

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

Back 23

slide

Front 24

Creep is _________

Back 24

mass wasting by the gradual downhill movement of sediment, influenced by freeze-thaw or wet-dry cycles

Front 25

Describe how a soil particle moves downhill during the freeze-thaw process.

Back 25

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

Front 26

Why would trees be J-shaped?

Back 26

The trunks become tilted in the downhill direction due to creep, but continue to grow toward the sun.

Front 27

A __________ is a common result of creep.

Back 27

broken retaining wall (or tilting of any object logged in the ground for a period of time where creep occurs)

Front 28

describe 5 classifications how rock and other material move downslope

Back 28

fall, slide, slump, creep, flow

Front 29

What is mass movement?

Back 29

movement of material under the influence of gravity alone

Front 30

How is a fall different from creep?

Back 30

Falls occur rapidly and in areas with high slope, whereas creep occurs slowly in areas with low slope

Front 31

How are slumps and slides related?

Back 31

Slumps are a type of slide in the special case where the rupture surface is curved

Front 32

How are debris avalanches and flows related?

Back 32

Debris avalanches are large, rapid flows of rock.

Front 33

What type of mass movement event requires the addition of water?

Back 33

flow

Front 34

A piece of gravel is resting on a slope. Which of the following best describes how the gravitational force pulling the gravel downward will vary with the inclination of the slope?

Back 34

gravitational force will decrease as the slope angle decreases

Front 35

______ is unsorted sediments generated by glaciers

Back 35

till

Front 36

what is permeability

Back 36

ability to transmit water

Front 37

Landslide

Back 37

a general term for rapid mass wasting often associated with destruction

Front 38

How might a wildfire influence mass wasting?

Back 38

There are a couple ways. One is the removal of vegetation. Which can cause the sediment to loosen because the roots were anchoring the sediment. Also, fire can make soil more resistant to retention of water, thus causing water to accumulate at the surface.

Front 39

What term denotes the exposed, crescent-shaped rupture surface at the head of a slump?

Back 39

Scarp

Front 40

An accumulation of rock debris at the base of a cliff.

Back 40

talus

Front 41

Name two basic types of slides

Back 41

Rotational slides, and translational slides

Front 42

The most rapid type of mass movement is

Back 42

rock avalanche (rockslides)

Front 43

Name the 3 basic types of motion in mass wasting

Back 43

fall, slide, and flow

Front 44

why can rock avalanches move at such great speeds?

Back 44

Rocks literally float on air as they move downslope, because air becomes trapped and compressed beneath the rock

Front 45

Rockslides occur when

Back 45

blocks of bedrock break loose and slide down a slope

Front 46

If large portions of consolidated material breaks loose and slides down a slope it is termed what?

Back 46

debris slides

Front 47

During what season does solifluction in the arctic occur? Explain why it occurs only during that season

Back 47

Summer because the top soil melt and the water cant percolate into the permafrost layer so solifluction occurs

Front 48

Events that initiate downslope movement is called a

Back 48

trigger

Front 49

liquefacttion

Back 49

Intense ground shaking during earthquakes cause water-saturated surface materials to lose strength and behave as fluid like masses that flow

Front 50

Hydrologic cycle

Back 50

The unending circulation of Earth's water supply. The cycle is powered by energy from the Sun and is characterized by continuous exchanges of water among the oceans, the atmosphere, and the continents.

Front 51

infiltration

Back 51

The movement of water into rock or soil through cracks and pore spaces.

Front 52

The maximum rate at which soil can absorb water.

Back 52

infiltration capacity

Front 53

runoff

Back 53

Water that flows over land rather than infiltrating into the ground.

Front 54

Transpiration

Back 54

The release of water vapor to the atmosphere by plants.

Front 55

As an erosional process, how is mass wasting unique from wind, water, and ice?

Back 55

Mass wasting does not require a transporting medium.

Front 56

What is the estimated amount of total dollar losses from landslides in the United States?

Back 56

4 billion dollars

Front 57

A movement of fairly coherent material along a well-defined surface is called a __________.

Back 57

slide