Deformation

There is a great deal of folding that takes place in the crust of the earth apart from the mountain building that goes on near subducting trenches. A geologic map of any region will show synclines, anticlines, isoclinal folds, etc. This folding is just the same as when a person presses hard against a lump of clay.

The folds come about as sediments, laid down on a plane harden sufficiently to form a cohesive layer, and are then subjected to pushing and shoving of the earth's crust from the forces of plate tectonics. The crust deforms and cracks, folding into hills and valleys which are then eroded, starting the whole process all over again.

This is a view of the Earth.
Click on image for full size version (40K GIF)
Image from: NOAA

Go to a listing of Rocks by mineral group

Last modified November 15, 1997 by the Windows Team

The source of this material is Windows to the Universe, at http://www.windows.ucar.edu/ at the University Corporation for Atmospheric Research (UCAR). © The Regents of the University of Michigan. Windows to the Universe® is a registered trademark of UCAR. All Rights Reserved. Site policies and disclaimer