Presentation on theme: "Tuesday, January 6, 2015 Turn in homework on front counter Get out the definitions you did for homework Get out yesterday’s notes on mass movements."— Presentation transcript:
Tuesday, January 6, 2015 Turn in homework on front counter Get out the definitions you did for homework Get out yesterday’s notes 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 Slumps process 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.
Solifluction Solifluction 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 slumping See earth slump
Deforestation Deforestation is the permanent destruction of forests in order to make the land available for other uses
Slope angle reduction If 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.
Afforestation Afforestation 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.
Drainage Areas 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 protection Areas 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 Surface Get Both pages of the Changing Earth’s Surface worksheet Answer all questions on your own paper Due by the end of class
Homework Answer 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