mass movement Flashcards
what is mass movement?
the movement of material down a slope under the influence of gravity
what four categories can mass movement be put into?
creeps, flows, slides and falls
what is meant by soil creep?
the movement of soil particles downhill
why do particles rise and fall in soil creep?
wetting and freezing forming shallow terracettes
where does solifluction mainly occur?
in periglacial environments
what happens in solifluction?
when the top layers thaw during summer and the surface layers flow over the frozen layers
what is meant by mudflows?
an increase in the water content of soil can reduce friction - leading to earth and mud to flow over underlying bedrock or slippery materials e.g. clay
where do rockfalls occur?
on sloped cliffs (over 40o)
when do rockfalls occur?
when exposed to mechanical weathering - leading to scree building up at the base of the slope acting as an input to the coastal zone
what happens in a landslide?
heavy rainfall can reduce friction in cliffs - occurs when a block of intact rock moves down the cliff face very quickly along a flat slope
what happens in a slump?
slop is curved - the land collapses under its own weight due to PWP - creates a terraced appearance
how does runoff occur?
water may erode the cliff ace or pick up sediment that enters the littoral zone
