weathering and slope processes

Question 1

types of weathering

Answer 1

chemical - decomposition of minerals
physical - distingirtion of rocks without chemical change to minerals
biological - decay and sitingration of rock minerals due to biological processes

Question 2

chemical weathering

Answer 2

most important influence is type of rock , least stable minerals are formed under extreme heat and pressure conditions
second most important is water - availability, temperature and chemicals

Question 3

rock type

Answer 3

determines mineral content , texture, porosity, structure bulk properties hardness elasticity and strength

Question 4

water

Answer 4

avialiabilty of water increased weathering
temperature influxes rate of chemical changes
acidity condensation in the atmosphere take sin co2 , co2 dissolves in water and creates carbonic acid

Question 5

solution weathering

Answer 5

example of carbonization , removal of minerals in dissolved state or solution

Question 6

hydrolysis and hydration

Answer 6

moistening of rocks causing chemicals change and expansion of minerals
new minerals are weaker and flake off rock

Question 7

oxidation reduction

Answer 7

oxidation - loss of electrons minerals react with atmospheric oxygen , al and fe rust dominant in tropical areas
reduction 0 gain of electrons oxygen removed from mineral

Question 8

chelation/complexing

Answer 8

mineral interaction with organic acids minerals are more soluble

Question 9

hydrothermal alteration

Answer 9

movement of super hot mineral rich water changeing mineral composition
associated with proximity to magma chambers or during metamorphism

Question 10

physical weathering

Answer 10

distingeration of rocks without chemical changes , type of debris depends on rock type and structure , increase step exposed surface area making it more susceptible

Question 11

initiated by the formation of cracks through

Answer 11

differential expansion of rock minerals - exfoliation
chemical decomposition along joints and planes
crystal growth processes - frost weathering and haloclatsy

Question 12

exfoliation

Answer 12

uplift an surface erosion = expose buried rock

less pressure and stress results inc racks developed parallel to surface

Question 13

frost weathering

Answer 13

water increased in volume by 9% when it freezes

wate rin cracks joints and pores expands under freezing temperatures

Question 14

haloclasty - salt weathering

Answer 14

when water in pores of rock evaporate they create crystals bursting the rocks when they grow , important in areas where there is more evaptrasnspiration than precipitation

Question 15

biological examples

Answer 15

root action - physical and chemical
bioturbation- soil mixing by worms and animals
lichens - draw minerals dorm rocks, expand and contract

Question 16

humans weathering examples

Answer 16

pollution increases so does weathering
quarrying and mining deforestation exposes surfaces
farming and fertilizing changes soil formation

Question 17

slope processes - shear stress

Answer 17

gravity plays a major role in shaping landscapes
shear stress - driving forces causing material to go downslope as a factor of gravity and weight
resisting force that counteract the downslope driving forces contribute to the slopes shear strength - friction and cohesion

Question 18

ange of repose

Answer 18

max angle at which a solid or granular material remains at rest
factor of type of material , vegetation cover, soil moisture and drainage and land use

Question 19

factor of stability

Answer 19

stability of slopes can be calculates using F - factor of stability = shear strength (resisting forces ) / divided by shear stress (driving forces)
f = 1 critical threshold (resisting = driving )
f>1 slope is stable (resisting ?driving)
f<1 slope is unstable (resisting

Question 20

Mass movement (mass wasting, slope failures)

Answer 20

dominated by gravity overcoming the resisting forces often large amounts of material i.e. falls slides rows and creep

Question 21

hill slope/soil erosion

Answer 21

hilltop erosion due to the action of water or another agent like wind and ice eroding soil form a slope
result in reduction of soil quality productivity
examples - wash sheet erosion
rain splash erosion
rills and gully erosion

Question 22

falls rock or debris

Answer 22

material free fall form steep slopes , due to changes in environmental contions and earthquakes disturbances ( freeze thaw or saturation

Question 23

slides

Answer 23

sudden movement of a large amount of unsaturated material along a shear plane can be trasnaltionla or rotational slump depending on moving plane shape flat or concave shape

Question 24

flows ( earth debris mud)

Answer 24

viscous deformation of slope material, require large amounts of water

Question 25

creep

Answer 25

episodic heave and settlement of individual particles
- cycles of wed dry diurnal temperature variations (freeze-thaw) , grazing and digging animals
solifluction - slow movement but more water

Question 26

wash sheet erosion

Answer 26

shallow Flo of water across a sloped surface
removes soil nutrients an dseeds
effective eon bare surfaced large areas

Question 27

rainsplas erosions

Answer 27

caused by the impact of raindrops on bare soil

effectiveness depends on slope angle intesitio od rainfall, vegetation cover soil texture

Question 28

rills and gullies

Answer 28

micro channels featuring hilltop and fluvial processes result for the concnetatrion of w=runoff during and after precipitation events
rills ar esmall and easily removed, gillies are large and permanent