Mass movement

Question 1

Mass movement def

Answer 1

Process where regolith moves downslope

Question 2

Regolith

Answer 2

Loose weathered material like rock, soil and mud that is poorly held together

Question 3

factors influencing mass movement

Answer 3

Human interaction - cutting out motorwaya
Gradient - steeper= higher risk
Water content - more water is slippier
Slope materials - more compacted better
Vegetation - Binds soil together
Tectonic activity - vibrations cause instability
Volcanic activity - Material released cause lahars

Question 4

Soil creep

Answer 4

Slow
Gentle slopes
Freeze thaw action - soil expands + contracts
Wetting + drying cycles - water makes soil expands + contracts

Question 5

Soil creep effects

Answer 5

Forms terracettes
Curved tree trunks
Build up at the base of walls causing collapse

Question 6

Terracettes

Answer 6

Ridges that run parralel to the slope giving it a stepped appearance from the forward movement of soil

Question 7

Landslide

Answer 7

Fast
Bedding planes fracture so underlying sedimentary rock dips down and loose regolith on top alides off
Triggered by rainfall + seismic activity

Question 8

Bogburst

Answer 8

Fast
Caused by saturated peat moving downslope blanket bogs because the stabilising vegetation withers in winter and the bog is oversaturated by rain in summer. Can be triggered by wind farm excavation

Question 9

Derrybrien bogburst year

Answer 9

2003

Question 10

DerryBrien - which blanket bogs

Answer 10

Slieve Aughty mountains

Question 11

How derrybrien happened

Answer 11

Lots of peat was excavated for a wind farm + left in piles beside the excavation side for the summer - dried, cracked + contrated. November rain oversaturated - bogburst

Question 12

Derrybrien - How much peat

Answer 12

Half a million tonnes

Question 13

Derrybrien peat spread how far

Answer 13

2.5km from site