Slope Processes and Development

Question 1

describe a slope in an arid area?

Answer 1

jagged or straight due to mechanical weathering or shestwash

Question 2

describe a slope in a humid area?

Answer 2

rounder
due to ecumenical weathering
soil creep
and fluvial transport

Question 3

describe a slope in the tropics?

Answer 3

humid weather means domination of chemical weathering
due to hot wet conditions and avalibility of organic acids

deep flat produced favouring low slope angles

Question 4

what is revoking?

Answer 4

the superficial and unconsolidated material at earths surface

including soil scree weathered bedrock and deposited material

prone to downslope movement (due to unconsolidated nature)

clay rich are particularly unstable due to ability to hold water

Question 5

how can soil structure and texture influence slope development?

Answer 5

clay soils hold more water

dee clay on a slope where vegetation has been removed will offer very little resistance to mass movement

Question 6

how can vegetation affect slope development?

Answer 6

can decrease surface runoff through storage and interception

deforested slopes are exposed to intense erosion and filleting

vegetarion can increase chance of major landslides

Question 7

dry mass movement

Answer 7

rock fall

Question 8

fluid mass movement

Answer 8

mud flow

Question 9

very slow mass movement

Answer 9

soil creep

Question 10

fast mass movement

Answer 10

avalanche

Question 11

what is mass movement

Answer 11

large scale movements on the earths surface not accompanied by a moving agent such as a river or ocean wave

Question 12

what are the most important factors in determining mass movement

Answer 12

gravity
slope angle
pore pressure

Question 13

what factors influence slope development

Answer 13

rock type 
climate
regality
soil
aspect
vegetation

Question 14

what two factors cause slope failure

Answer 14

reduction in internal resistance SHEAR STRENGTH of slope

Increase in SHEAR STRESS of the slope (the forces attemption to pull the material downslope)

Question 15

what is the effect of gravity on mass movement

Answer 15

moves material downslope

sticks partciles to slope

Question 16

where do slip planes occur

Answer 16

at the junction of two layers
at fault lines
at a joint
along a bedding plane
when shear stress is rested than shear strength

Question 17

Heave/creep

Answer 17

slow
small scale
occurs mostly in winter

indidcual soil particles are pushed to surface by wetting heating or freezing of water
particles move at right angles to the surface as it is the path of least resistance
fall under the influence of gravity when the particles have dried, cooled or water has thawed

net movement downslope

Question 18

Talus creep

Answer 18

slow movement of fragments on scree slope

Question 19

what does the majority of soil creep movement come from

Answer 19

75% induced by moisture and so volume change

Question 20

how are individual soil particles heaved to surface?

Answer 20

wetting
heating
freezing

Question 21

what feature can heave form

Answer 21

terracettes

Question 22

what are the initial causes of falls

Answer 22

weathering e.g. freeze thaw or disintegration

or erosion prising open lines of weakness

Question 23

how can the length of rock fall influence scree

Answer 23

long - rounded scree

short - relatively straight

Question 24

what do falls cause on rock faces

Answer 24

retreat

Question 25

where do falls occur

Answer 25

steep slopes greater than 40 degrees especially bare rock faces where joints are exposed

Question 26

when do slides occur

Answer 26

when an entire mass of material moves along a slip plane

Question 27

different types of slides

Answer 27

rotational slides - producing series of massive steps or terraced rockslides or landslides or material rock or regith

Question 28

when do slides commonly occur

Answer 28

weak rocks steep slopes active undercutting change in the water content of slipe or very cold conditions

Question 29

what type of rock is vulnerable to slip planes and why

Answer 29

clay because it has little shear st engraved | slip plane is concave curve and the slide occurs the mass will be rotated backwards

Question 30

when do loose rocks stone and soil move downslope

Answer 30

when downslope force exceeds resistance produced by friction and cohesion

Question 31

when does a landslide occur

Answer 31

when material moves downslope due to shear failure at the boundary of the moving mass

Question 32

what are landslides sensitive to and why

Answer 32

water content reduced the strength of the material by increasing internal pressure this pushes particles apart weakening the links between them water adds weight to mass increasing downslope force

Question 33

what type of rocks do slumps occur on

Answer 33

weaker rocks | especially clay

Question 34

how do slumps and flows differ from landslide

Answer 34

high water content | smaller particles

Question 35

how does a flow differ from a slump

Answer 35

flows are more continuous less jerky more likely to contort mass material involved is predominately fine particles e.g. deeply weathered clay

Question 36

when does a slump occur

Answer 36

when clay absorbs water becomes saturated exceeds liquid limit flows along a slip plane frequently the base of a cliff has been undercut and weakened by erosion thus reducing its strength

Question 37

example of a slump

Answer 37

Average 21 October 1966 144 killed 116 of which were school children

Question 38

fact about the material in a slump

Answer 38

33% is fine grained

Question 39

how does the speed of flows vary

Answer 39

mudlflows are much faster than earth flows and more fluid higher water content enables material to flow across gentler angles

Question 40

what are avalanches

Answer 40

rapid movements of snow ice rock or earth down a slope | snow and ice may pick up rocks and or earth

Question 41

in mountainous steep areas how does a rock fall differ from a rock avalanche

Answer 41

rock avalanche is large scale movement to material rock fall could be individual rocks

Question 42

where are avalanches common

Answer 42

steep slopes over 22 degrees especially on north facing slopes where the lack of sun inhibits stabilisation of snow mountainous areas

Question 43

dry acalanche

Answer 43

newly fallen snow falls off older snow | winter

Question 44

wet avalanche

Answer 44

in spring partially melted snow moves often triggered by skiing

Question 45

what is a debris avalanche

Answer 45

rapid mass movement of sediment often associated with saturated ground conditions