Mass Movements

Question 1

Free fall

Answer 1

• Material detaches from a slope and then free falls through the air, or bounces and rolls downslope

Question 2

Slide

Answer 2

• Material (either rock or regality) that slides along a surface of rupture

Question 3

Flow

Answer 3

Continuous movement of rock, regolith, or both that behaves as a high viscosity liquid

Question 4

Rock falls are…

Answer 4

extremely rapid

Question 5

Debris/earth falls are..

Answer 5

Rapid to extremely rapid

Question 6

Rock slides are…

Answer 6

Very slow to extremely rapid

Question 7

Debris/earth slides are…

Answer 7

Very slow to very rapid

Question 8

Rock slumps are…

Answer 8

Extremely slow to moderate

Question 9

Debris/earth slumps are…

Answer 9

Very slow to very rapid

Question 10

Distinguishing the speed of motion:

Answer 10

• Slow (cree

Question 11

What factors make up the criteria for the classification scheme or mass movements?

Answer 11

• Nature of the mixture of solids (rock, debris, or earth materials)
• Type of motion (fall, slide or flow)
• Velocity of motion (avalanche, flow, or creep)

Question 12

Creep

Answer 12

Is slow and only detected by dislocation or bending of features at the surface

Question 13

Debris Avalanches:

Answer 13

Are very rapid flows of rock, regolith, vegetation and/or sometimes ice

Question 14

Flow

Answer 14

Are the continuous movements of rock, regolith, or both which behaves like a high viscosity liquid. Flow occurs on different scales

Question 15

Rock creep:

Answer 15

Is extremely slow to slow (slow flows)

Question 16

Debris/earth creep:

Answer 16

Is extremely slow to slow

Question 17

Debris/earth flow:

Answer 17

Is very rapid

Question 18

Debris avalanche (rock and regolith):

Answer 18

Is very rapid to extremely rapid

Question 19

When are rock falls common?

Answer 19

They are common where rock is highly jointed and on a steep slope

Question 20

Talus

Answer 20

Is the loose material that piles up at the base of steep slopes. Lack of vegetation/soil on talus indicates that material is actively accumulating

Question 21

Planar slides:

Answer 21

Move downslope in contact with a surface of rupture, typically along bedding planes, foliation, or joint planes oriented parallel to the slope

Question 22

Slump:

Answer 22

Is the curved rotational slide surfaces that are scoop shaped and usually form in regolith, poorly consolidated, or weak rock where bedding/joints do not influence failure

Question 23

What forces AFFECT slope stability?

Answer 23

• Gravity force
• Friction
• Cohesion

Question 24

Gravity force:

Answer 24

In order for motion to happen, the gravity force parallel to the surface must be greater than the resisting strength

Question 25

Friction

Question 26

What increases friction?

Answer 26

More roughness = more friction

Question 27

Cohesion

Answer 27

Is the attraction of particles at the atomic level

Question 28

What has little cohesion?

Answer 28

Loose sand and gravel

Question 29

What factors DETERMINE slope stability

Answer 29

Angle of repose

Vegetation

Question 30

Angle of repose

Answer 30

The maximum angle of stability at which no movement occurs as determined by the friction, cohesion, and particle shape

Question 31

Vegetation

Answer 31

Is very important as roots penetrate and bind together regolith and absorbs water from precipitation

Question 32

Arid Climates

Answer 32

Have low vegetation abundance and slow rates of weathering and surface water removes most regolith particles very quickly as they loosen from bedrock

Question 33

Angle of sliding friction

Answer 33

The angle at which the particles start to slide