Mass Wasting – Flashcards

any gravity-driven downslope movement of rock or soil

sudden downslope movement of earth materials (falling, slumping, sliding, and flowing)

downslope movement of a coherent block of material that slides along a curved fault plane

very slow (gradual) downslope motion of material -freeze-thaw cycles

rocks that detach from the high part of a steep slope and fall under the force of gravity

sudden and rapid movements that happen when detached segments of bedrock break loose and slide downslope

•Coarse material •>50% of particles are coarser than sand

•Fine-grained material •Higher water content than debris flows and less than mudflows

•Fine-grained materials •High water content

An extremely rapid type of debris flow that typically begins with a rockfall or rock slide

a slow downslope motion of water-saturated soil overlying an impermeable (impervious to water) layer

void spaces between soil or sediment particles get filled with water, pushes grains apart

-Nature of movement -Rate of movement -Type of material moved

•Falling •Sliding •Slumping •Flowing •Creeping

cliffs

tilted bedding plane, exfoliation joints

fluid, high water content, can added with snow or air

freeze-thaw and wet dry cycles

unconsolidated materials mix together flowing down

-Weakening of earth materials; weathered material weaker than intact rock -Development of relief, the slopes down which masses move

resistance, normal, gravitational force

•Strong vibration - earthquakes •Loss of support - erosion, less resistant rocks at the base, slope failure •Prolonged rainfall - saturation, Weaken, lubricant •Volcanic activity - mix of loose sediment

bedding planes, exfoliation joints, metamorphic foliation planes

size of the materials (coarse or fine)

geographical location of occurrence (one is sub-polar, one is moderate climates)

material type, slope angle, water content, vegetation, climate

the stronger the material, the more stable it is (however the material below should be strong to support)

the lesser the angle, the more stable it is (less gravity attraction)

the less the water content, the more stable it is (less damp, strong support)

the more the vegetation, the more stable it is (the root hold on the soil)

the drier the climate, the more stable it is (less rainfall area is better)

removal of vegetation area, expansion of urban areas,