Mass Wasting It’s all about the GRAVITY ….and the slope and the angle of repose ….and the kind of material …..and how much water Video: http://www.youtube.com/watch?v=JrV4uCVwmfk http://www.youtube.com/watch?v=mknStAMia0Q http://www.youtube.com/watch?v=zJUTNR6_fnk http://www.youtube.com/watch?v=t- 8B3pEEOXQ&feature=relmfu

Soil Creep – 1to 10 mm/yr

Soil Creep

Solifluction

Solifluction

Rockslides Colorado Andes

Slump

Slump

Avalanche

Mudslide/Mudflows

Mudslide

What causes the energy behind mass wasting to increase? How steep is the slope? What are the size and shape of the particles? What is the hill or slope made of? How deep is the weathered material? What is the ground cover, if any? How stable is the ground? How much water is there? All of these factors will determine whether or not a slope failure occurs.

Size and Shape of Particles Jagged pieces on a slope are less likely to move and can create a steeper angle of repose – more material once it does move. Rounded pieces more likely to roll, can't create a very steep slope Larger pieces are more likely to move Smaller pieces can create a steeper angle of repose, and the steeper the angle, the more likely it will move.

What is the material of the slope? Snow is the least stable Air and water in solid and liquid form A few degrees change in temperature changes stability Clay is also very changeable Added water makes paste, but increases mass causing slide

How deep? The deeper the soil, the more likely it is to slide

Ground Cover Roots of trees and plants can keep ground cover in place Clear cutting Road sides – Slow and gradual movement of soil down hill Usually under intense pressure Especially in pastures where grass is short and roots are less extensive Soil slides away beneath vegetation

Slope Stabilization

Be able to label:

Your job – Create a visual (draft) essay Use and 11X17 sheet of paper and create a set of notes – essentially a draft visual essay Note types of mass wasting – an image is fine. Explain what types of conditions increase or decrease the likelihood of a mass wasting event. Essentially, take the notes from the power point and include them in your essay. Illustrate different ways governments/contractors work to stabilize slopes. This is where your need to focus your research.

Assessment Do you demonstrate an understanding of Mass Wasting? Do you suggest several types of strategies to decrease mass wasting in several different types of conditions? ? Does your visual essay include notes and images organized in a way that is visually appealing and is easy to read? This is a draft in the sense that you will only have three hours of class time to work on this. It is not a poster project, but a note-making project.