Test 4 Material Flashcards
what is mass wasting
rock on unstable slopes has the potential to move downslope under the influence of gravity, important in mountain errosion
Subaerial (slow to fast)
creep, solifluction, slump, mudflow, debris flow, lahar, rockslide, debris slide, avalanche, debris fall
creep
slow gradual downslope movement on a slope
solifluction
in places where slopes are underlain with permafrost, causes a melted layer to flow down slopes in the brief summer thaw
slump
a slow-moving event which rock does not disintegrate but stays somewhat coherent
mudflow
or mudslide, a moving slurry of mud by heavy rain
debris flow
a slurry consisting of a mix of mud and pebble to boulder sized fragments
lahar
mudflow of volcanic ash and water from the melted snow
rock slide
a sudden movement of rock down a non-vertical slope
snow avalanche (dry)
formed when the snow mass contains no liquid water, tumbles as cloud of powder
snow avalanche (wet)
formed at warmer temperatures, move as a mix of solid and liquid water
rock avalanche
when the material in a rock/debris fall mixes with air and forms a turbulent cloud that races downslope
rockfall
occur when a mass free falls from a cliff, commonly happen along joints
debris fall
when debris free falls
talus
a sloping apron or rocks along the base of a cliff
three stages of mass wasting
- fracturing and weathering of substrate
- development of relief, provides a slope to move down
- an event that sets it in motion
resistance force
granular debris tends to pile up and produce the steepest slope
angle of response
the angle depends partially on the shape and size of the grains, which determine the amount of friction
what causes slope failure
shocks, vibrations, and liquefaction, changing slope loads, changing slope strength
identifying dangerous mass wasting regions
slump head scarf, tilted trees, piles of loose debris at base of hill, bumpy land, manmade features crack over time
preventing mass wasting
- revegetation, and regrading
- reducing subsurface water, prevent undercutting
- building safety structures
- controlled blasting of unstable slopes
the hydrologic cycle
circulation of earths water supply
sources of earths water
streams make up a small percentage of freshwater
forming streams
- begins as sheetwash
- sheetwash digs tiny channels called rills
- rills down cut, develop into streamflow