key terms Flashcards
1
Q
ridge push
A
- when a mid ocean ridge rises from magma and convection currents, pushing plate up
- gravity acts, and plate is pushed down the asthenosphere due to gravity under mid oceanic ridges
2
Q
slab pull
A
when a plate subducts, the plate sinking into the mantle pulls the rest of the plate (slab) with it, causing further subduction
3
Q
hotspots
A
- area of volc activity not related to plate boundaries
- hot magma plumes from mantle rise and burn through weaker parts of crust
- creates volcanoes and islands
- plume stay in same place, but plates move so chain of islands form (Hawaii)
4
Q
rainsplash
A
- impact of the rain droplets dispaces soil particles, detaching from rest of the ground.
5
Q
sheetwash
A
- overland flow where shallow sheet of water flows over surface of slope, causing top layers of slope to be transported downhill
- when water cant infiltrate, so flows over
6
Q
rills
A
- small streams developed by erosive flowing water
- develop on slopes, as water flows downwards naturally due to gravity
- rills can develop to large ravines (gullies)
7
Q
mass movement
A
- large-scale movement of materials on a hillslope, where stress exerted exceeds the internal strength of the hill, = instability
- always downhill (gravity)
8
Q
Heave
A
- occur on slopes made w cohesive materials and non-cohesive materials
- frost heave + soil creep (2 diff types)
- slowest + most common form
- when soil particles are pushed upwards, and move down hill
- soil creep as clay soil swells when wet, so pushes soil above it upwards
- frost heave ice expands as freezes, pushes soil above it
9
Q
flows
A
- cohesive materials (silts + clays)
- faster than heaves, but slower than the rest
- controlled by moisture in slope.
- if soil oversaturated, cohesive bonds within soil break, making soil move downhill like viscous liquid
- mudflows often when heavy rainfall conditions
10
Q
falls
A
- occurs on rocky slopes
- very sudden movement, not dependant on a factor (e.g. rainfall like flows)
- triggered by freeze thaw processes, seismic waves, gravitational stress
11
Q
slides
A
- fast movement of rock, debris or earth down a slope
- occur along faults in the rock
- can be triggered by seismic waves / gravitational stress
- large scale, lots of material moved in short time
12
Q
weathering
A
the breakdown of rocks in situ (in a fixed place)
13
Q
formation of volc island arcs
A
- convergence of 2 plates, driven by convection currents in mantle
- subduction of denser of the plates
- melting of subdictung plate @ benioff zone
- rise of magma through non subducting plate, shoots out and lands in water
- forms volc island arcs