key terms

Question 1

ridge push

Answer 1

• 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

Question 2

slab pull

Answer 2

when a plate subducts, the plate sinking into the mantle pulls the rest of the plate (slab) with it, causing further subduction

Question 3

hotspots

Answer 3

• 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)

Question 4

rainsplash

Answer 4

• impact of the rain droplets dispaces soil particles, detaching from rest of the ground.

Question 5

sheetwash

Answer 5

• 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

Question 6

rills

Answer 6

• 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)

Question 7

mass movement

Answer 7

• large-scale movement of materials on a hillslope, where stress exerted exceeds the internal strength of the hill, = instability
• always downhill (gravity)

Question 8

Heave

Answer 8

• 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

Question 9

flows

Answer 9

• 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

Question 10

falls

Answer 10

• 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

Question 11

slides

Answer 11

• 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

Question 12

weathering

Answer 12

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

Question 13

formation of volc island arcs

Answer 13

• 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