Mass Movement Flashcards
what are the 6 types of mass movement
rockfall , landslide , rotational slip(slumping) , mudflow , solifluction , soil creek
what is rockfall
this is where rocks rapidly break away from a cliff face
what is rock called when it falls to the cliff foot
scree / talus
how can rockfalls be caused
it can happen rapidly by earthquakes
gradually by freeze thaw and when cliffs are eroded and undercut by the sea
why is rockfall frequent at the coast
because cliffs usually have a steep gradient so this makes rock more likely to fall from gravity
what is a landslide
movement of rock or other debris down a sloped cliff or land
where do landslides tend to happen and why
on cliffs made from soft rock or loose/deposited material because excessive rainfall makes it more lubricated so it’s more likely to slide down land
what can landslides cause and why
a loss of life because they are so rapid and dangerous
what is rotational slip
this is where rock/debris on a cliff slides down the cliff but the cliff is concaved(curved) causing a rotational movement
why does rotational slip occur
excessive lubrication means the cliff can’t cope with the amount of moisture meaning it has a greater gravitational pull so it slips down the cliff
what is the difference between the cliff rock and the rock that is falling during rotational slip
the rock falling is usually softer as it contains more moisture than the rock underneath
what is mudflow
where spikes or weak rock like clay and volcanic ash become so saturated that they flow downhill
how fast are mudflows and what can that cause
they are sometimes slow but mostly are very rapid and it can cause a loss of life
what affects the speed of mudflows
how much the soil or material is saturated
what is a lahar
where melted ice/snow combine with volcanic ash to cause rapid flows
