1 Flashcards
what are the two forms of weathering?
mechanical and chemical
what is weathering and how is it different from erosion ?
breaking materials down (decomposition of solid earth materials
erosion = movement of materials
why is water critical to weathering?
abundent on earths surface
-exists in 3 phases
1.it expands when it freezes
2. it has a high surface tension = capillary action(pulls itself along thin sheets of rock
sneaks in then expands and blows cracks oppen
3. water is a universal solvent
it has both positive and negative charge meaning it can disolve cations (+) and anions (-)
What are the processes of mechanical weathering?
Frost cracking
unloading/fracture
vegitation/roots
what is frost cracking?
thin film of water seeps into cracks and expands and cracks rock, happens repeatedly lengthening the crack
what is unloading?fracturing (exfoliation or sheeting)
rock is under pressure from all around it, then is exposed and only pressure on one side and other side expands like sponge and cracks at surface
what is vegitiation roots weathering?
roots crack stuff
what is chemical weathering?
breakdown of minerals and rocks through chemical reactions with (water,co2, oxygen, and organic acids)
what are the processess of chemical weathering?
hydration/hydrosis
oxidation
carbonation/solution
what kind of rocks do you need for landscape scale chemical weathering?
limestone and marble
what is karst?
forms caves and then collapses into valleys then sink holes, then karst valleys
-two things important for karst: precipitation and soluble rocks
what is mass wasting?
movement of earth material under force of gravity down
F=Gm1m2/d2
what is an angle of repose?
highest and most stable slope
what is a creep?
when something creeps along from frost
what is soilflection?
permafrost must exist
top layer of permafrost melts but lower layers do not, top part slides down hill, can happen with clays as well
what is a slump?
slower than a flow, slide or fall
curved plane of falure
intact rotated blocks
what is a flow?
turbulent motion of earth material down a slope
eroded bed plane
speed=water content
consists of mud, debris, water and earth
what is a slide?
flat plane rock structure
what is a fall?
crate a talis slope loose material forms ramp at bottom like at tiber dirt cliffs
Rock avalanche- Surtzstrom
you know what an avalanche is now make it a rock one, forces rocks to go a lot longer than usually posible, very high energy
what is a stream?
any channelized flow, even a river is a stream
what is watershed?
area above any reach that contributes water
what is a reach?
any defined segment of stream
what is a profile slope- Gradient?
slope form along a channel V=velocity S=sediment load E=erosion D=deposition
what is capacity as relates to a stream?
amount of sediment=amount of water
what is competence?
size of the particle
What is a thalweg?
area of a channel with highest velocity