Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Shear in Rocks
Name: Toby D.
Status: Student
Age: 30s
Location: N/A
Country: N/A
Date: December 12, 2002

I would like to know specifically what "general shear" is when mentioned with respect to strain in rocks?

This is a difficult concept to explain in this type of forum. I suggest that you review available textbooks in structural geology to get a better explanation. However, here is a shot at it.

General shear is a combination of two theoretical types of strain, pure shear and simple shear. In the case of pure shear, the material does not rotate, but is sort of "squished", to use a non-technical term in response to an applied stress. That is, the material uniformly elongates in one direction and uniformly shortens in the perpendicular direction.

Simple shear, on the other hand, involves a rotational strain in which in the material moves parallel to a given axis. (Think of a deck of cards being fanned.) In simple shear, the axis perpendicular to the shear plane does not shorten. (The deck of cards does not get thinner when it is fanned.)

In actual materials, neither of the two theoretical shear types are encountered in isolation. Instead, most shear deformation is some combination of the two. Consequently, geologists use the term general shear to describe the combined case.

Andy Johnson

Click here to return to the Environmental and Earth Science Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory