Erosion and sea level change Flashcards
Define ‘weathering’
The gradual breakdown of rock in situ or close to the ground surface in three different types; mechanical, biological or chemical.
Define ‘mass movement’
The movement of weathered material down a slope as a result of gravity
Define ‘rotational landslide’
The downward movement of a mass on a concave/ curved slip surface
Define ‘translational landslide’
The downward movement of material along a fault, joint or bedding plane said to be translational when the slip surface is straight
Define ‘block slide’
A translational slide of mass consisting and moving as a single unit of a few closely related units
Define ‘rock fall’
Similar to a block fall on slopes of over 40 degrees when material either bounces down the slip surface or falls vertically to form scree at the foot of the slope
Define ‘topple’
The forward rotation of a mass generally occurring around an axis
Define ‘debris flow’
A moving mass of loose soil, mud, soil and rock made weak by saturation that travels down a slope by the influence of gravity, at least 50% of the moving material must be the size of sand particles or larger
Define ‘debris avalanche’
When an unstable slope collapses and so the material is transported away from the slip surface and may slide over underlying rocks
Define ‘earthflow’
A downward flow of saturated fine grain material as an intermediate stage between a creep and mudflow
Define ‘creep’
Slow downward movement of weathered material indicated by slow but persistent tilting of trees
Define ‘lateral spread’
Rapid movement of material as a result of liquefaction
Define ‘carbonation’
The mixing of water with CO2 to form carbonic acid which reacts with minerals in the rocks
Define ‘oxidation’
The reaction of a substance with oxygen e.g. iron forms iron oxide which weakens the rock
Define ‘hydrolysis’
A chemical reaction of rock minerals with water e.g. feldspar in granite and rainwater forms clay
Define ‘freeze-thaw weathering’
When water enters a crack or joint expands 10% when it freezes exerting pressure on the rock causing the crack to widen
Define ‘exfoliation’
Mechanical weathering in which curved plates of rock are weathered away from the rock below to form exfoliation domes along joints in layers
Define ‘aeoliation’
Referring to the wind
Define ‘burrowing’
When birds e.g. puffins and animals burry into the cliff
Define ‘roots’
Plant roots grow into cracks into the slip surface and forces them to break wider when they thicken
Give some factors affecting erosion rates MM HA J W H/S R G
Mass movement Human activity Jointing Weathering Hard/ Soft rocks Geology
Give some factors affecting erosion rates C/D SA WR P C F
Concordant/ Discordant Sub-aerial marine processes Wave refraction Permeability Climate Fetch
Give some factors that affect morphology F CF ER H/D CP
Folds Coastal features Erosion rate Haff/ Dalmation Cliff profile
Give some factors that affect morphology BP/ J F C/D G
Bedding planes/ joints
Faults
Concordant/ Discordant
Geology
Describe salt crystallisation
The growth of sea salt crystals in cracks and pore spaces can exert a breaking force but less effective than freeze-thaw.
What’s the difference between flows and slides?
Flows are wet and fast
Slides are dry and fast
Describe soilfluction
Occurs mainly in tundra areas where the ground is frozen when the top layer thaws, the under layer remains frozen so saturated land flows over the subsoil
Give the flowchart of how sub-aerial processes affect the coastline
Rainfall - Saturated cliff - Heavier - Gravity causes cliff to fail - Slump - Bottom of the slump is eroded - Unstable cliff - Slumps again
President of Kiribati bought (1) of land on one of the (2) islands to grow food, source water and take refuge there. Sea levels are rising at (3)/yr and most of the land is less than (4). Sea levels are rising due to (5)
1 - 20km squared 2 - Fijian 3 - 1.2cm 4 - 1m above sea level 5 - thermal expansion
How much would the sea level rise if the Alpine glaciers, Greenland and Antarctica ice sheets melt?
AG - 0.6m
G - 7.3m
A - 56.6m
Give three ways in which sea level falls
- sea level falls and land rises or subsides at a slower pace
- land rises and sea level remains fixed
- the sea rises but the land rises at a greater pace
Give three ways in which sea level rises
- sea level falls and land subsides at a greater pace
- sea level remains fixed whilst land subsides
- sea level rises and land subsides, stays still or rises at a slower pace
What is the difference between eustatic and isostatic sea level change?
Eustatic - global change
Isostatic - local change e.g. ice sheets squashes the land and then rises again when the ice melts
Why is land rising in the N and W of England?
It was covered by an ice sheet so is rising due to isostatic recovery
Why is land sinking in the S and E of England?
The weight of the sediment in the Thames Estuary causes the crust to sink and relative sea levels to rise due to isostatic change and rising sea level due to global warming
