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counter• Get out the definitions

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on mass movements

Rock weathering

Weathering breaks down and loosens the surface minerals of rock so they can be transported away by agents of erosion such as water, wind and ice. There are two types of weathering: mechanical and chemical. Mechanical weathering is the disintegration of rock into smaller and smaller fragments.

Rock falls

ROCKFALL  is the falling of a newly detached mass of rock from a cliff or down a very steep slope. Rocks in a rockfall can be of any dimension, from the size of baseballs to houses.

Landslides

the sliding down of a mass of earth or rock from a mountain or cliff.

Earth Slumpsprocess of slope failure, in which

a mass of rock or unconsolidated material drops along a concave slip surface. Slump units move downslope as an intact block (without internal deformation of the landslide material) and frequently rotate backwards.

Soil creep

Creep is a very slow mass movement that goes on for years or even centuries. You can't see creep happening but leaning fences and poles and broken retaining walls show where it has taken place.

SolifluctionSolifluction is a special type of

creep that occurs in areas of permafrost

Mudflows

Mudflows are rivers of liquid and flowing mud on the surface of normally dry land, often caused by a combination of brush loss and subsequent heavy rains.

Rotational slumpingSee earth slump

DeforestationDeforestation is the permanent

destruction of forests in order to make the land available for other uses

Slope angle reductionIf it is determined that an area is

going to be prone to landslides due to a steep slope, soil can be moved in to reduce the grade (angle) to try and prevent the likelihood of mass movements along them.  If an area has been cut away, bringing in land to fill the void may also take much of the risk of mass movement away.

AfforestationAfforestation is planting trees and vegetation

in areas where currently none grows.  For the purposes of mass movements, this is done to stabilize the land by providing leaf litter and root structure.  Reforestation is the process of reclaiming a land to it original state, one it is found that be deforesting, it is susceptible to mass movements.  Replanting trees can increase drainage into the ground and prevent water from eroding the soil away.  Also, trees provide transpiration, which is how they soak up the water and evaporate it back in the air.

DrainageAreas in which it is determined

landslides may occur may set up drainage systems to divert water away from slopes and into established waterways.  This can be done by making troughs in the land that diver the water away or with pipes that bring the water around the areas in danger.

Surface protectionAreas may be covered with

vegetation or other natural material (like mulch) in order to protect it from flowing water or air.  This may be the easiest measure to protect against mass movement, but bring with it the obvious hurdle that it must be replenished at certain intervals if the material is just sitting on the ground, rather than planted in it.

Changing Earth’s SurfaceGet Both pages of the Changing

Earth’s Surface worksheetAnswer all questions on your own

paperDue by the end of class

HomeworkAnswer the LEQ “How are mass-

movements on steep and gentle slopes managed?”

Use your book and online resources

You must provide your sources of information

Be prepared to discuss your answer tomorrow