Chapter 15 Flashcards Preview

Geol 101 Lecture > Chapter 15 > Flashcards

Flashcards in Chapter 15 Deck (26):
1

Landslide

sudden event where large quantities of rock move downhill

2

mass wasting

downslope movement of rock, regolith, and soil under the direct influence of gravity

3

most rapid and spectacular mass-wasting events occur in

areas of rugged, geologically young mountains
are changed to more subdued terrain

4

role of water

when sediment pores fill with water, cohesion among particles are destroyed
Water can lubricate materials
water adds weight to a mass of material

5

dry sand grains

bound mainly by friction to one another

6

damp sand grains

small amounts of water increase the cohesion

7

wet sand grains

saturation reduces friction and causes the sand to flow

8

Heavy rains trigger

debris flow

9

angle of repose

unconsolidated granular particles assume a stable slope

10

mass wasting can be triggered by

oversteepened slopes that are unstable; ex: stream cuts, oversteepen slope

11

landslides without triggers

slope material weakens over time
some landslides are random, unpredictable events

12

fall

the free fall of detached pieces
Talus slopes are built by rock falls

13

slide

occurs when there is a distinct zone of weakness separating the slide material from the underlying material

14

rotational slide

surface of rupture is concave up

15

translational slide

material moves long a flat surface

16

flow

occurs when material moves downslope as a viscous fluid

17

rock avalanche

most rapid type of mass wasting
rocks float on air as they move downslope

18

creep

moves particles a few milimeters per year

19

slump

movement of mass of rock or unconsolidated material as a unit along a curved surface

occurs along oversteepened slopes

20

rockslide

occurs when blocks of bedrock slide down a slope
-fast and destructive
-triggered by earthquakes, rain or melting snow, common during spring

21

debris slide

occurs when unconsolidated material slides down a slope

22

debris flow

rapid form of mass wasting that involves the flow of soil and regolith with water
often confined to channels and canyons

23

Lahar

debris flows composed mostly of volcanic materials

24

Earthflows

form on hillsides in humid regions during heavy precipitation or snowmelt
commonly involve materials rich in clay and silt

25

solifluction

downslope movement of water logged soils
Common in regions uderlain by permafrost

26

permafrost

permanently frozen ground
especially around arctic ocean