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
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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

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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)
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4
Q

rainsplash

A
  • impact of the rain droplets dispaces soil particles, detaching from rest of the ground.
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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
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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)
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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)
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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
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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
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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
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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
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12
Q

weathering

A

the breakdown of rocks in situ (in a fixed place)

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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
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