weathering and mass movement

landform

single unit/feature of earth’s topography (lake, mountain, etc)

landscape

mosaic of landforms

mechanical weathering

rock fracturing by expansion

chemical weathering

rock softening by chemical action

frost action

type of mechnical weathering where water expands when it freezes

salt crystal growth

type of mechanical weathering where evaporation of ground water causes growth of salt crystals

exfoliation/unloading

type of mechanical weathering where deep-forming rocks are compressed by rock above (exposed rock expands / cracks in layers parallel to surface)

oxidation

type of chemical weathering where minerals containing iron are oxidized or reduced

acid

type of chemical weathering where hydrogen replaces a cation in mineral structure

dissolution

type of chemical weathering where water dissolves minerals by hydrating cations and anions until they become dissociated from each other

what determines topographic relief

balance between erosion + tectonic isostatic relief

• erosion exceeds uplift→ relief is reduced

  • relief decreases→ erosion decreases

low angle slope

friction exceeds downhill gravitational component

steep slope

downhill gravitational component exceeds friction

angle of repose

angle at which a material on a slope is stable

creep

slow downhill movement of soil

landslides

blocks of weathered rock and soil move down a slope

slump

landslide that rotates along a slip plane

rock slide

steeper slopes/ harder rocks than a slump

earth flow

saturated soils flow downslope

• small flow: soil slip

  • large flow: debris flow

rock fall

blocks of weathered/solid rock fall downslope (produce talus cones that accumulate at the bottom)

you examine a bright red weathered rock, this is an example of…

oxidation of iron in minerals