Mass Wasting

You already know that there are many ways of weathering (breaking up) a rock!!!  Probably more ways than you ever wanted to know.  You also know that water (as well as ice, and wind) can erode (transport) matter seaward.  However, that is not the only way ...

Matter can simply "fall" under the force of gravity.  This is known as mass wasting! Geologists categorize mass wasting events with terms like a "slide", a "fall", or a "flow" .  In either case, great quantities of matter is transported downward (quickly) due to gravity and is genetically labeled - landslides.  And these events usually make headlines and often result in a loss of property or even life.

A slump event is usually caused by the supporting material below giving away.  A river might undercut the lower layers of a valley wall and the material above it is no longer supported ... and down it goes.


Permission from http://www.cs.umt.edu/GEOLOGY/

 

This image above shows a rock slide in Yosemite (July 10, 1996).  This killed one hiker!


Permission from NOAA

Earthflow (above) can result when heavy rains (or snow melt) weaken the underlying soil.

On May 3, 2003 the state of New Hampshire was in a state of confusion and a bit red faced when its famous monument "Old Man of the Mountain" had a face lift ... err .. make that a face off ... due to a mass wasting event.  Since these state quarters are now flawed, send any you have to me for proper disposal.

     

            Before                                                                                              After

Photos by AP - Jim Cole

 


Permission from  http://www2.lehigh.edu/home.html

An Avalanche may be of rock, ice, or both.
 
 


From USGS

A mudflow (above) is common on the slopes of volcanoes or during intense flooding.
Click here to see a movie on the mudflow caused by Mt. St. Helens


From USGS

A sinkhole (above) occurs when an underground cavern collapses.
 

To avoid repetition, the unit on erosion discusses other types of cataclysmic mass wasting events such as Debris Flows, Mudflows, Jökulhlaups (pronounced "yo-kul-h-loip"), and Lahars.  Click here to see this material

Creep


These fence poles were once vertical.  Some creep made them useless.  Permission from  http://www.cs.umt.edu/GEOLOGY/

Creep - The greatest volume of matter "wastes" downward slowly .... very slowly ... in a process called Creep. This is similar to the warning label in cereal boxes - "some settling may occur"!  Every spring I have to dig out exposed rocks in my yard.  These rocks didn't move upward .. the soil around them settled down.

This is cause by:

 

©Jim Mihal 2004, 2006 - all rights reserved