Physical Geology Introduction
FOLDS, FAULTS and DEFORMATION
Stress
Compressive = > <=
Tension < >
Shear =>
<=
Strain
Elastic - Recoverable
Brittle Behavior
Plastic - Non Recoverable
Ductile Behavior
Orientation of Features
The INTERSECTION of two planes defines a
straight line
Let one plane be the surface of the Earth and
the other be an inclined geologic unit
This is the STRIKE of the inclined unit
The DIP is the angle that the inclined unit
makes with the surface
FOLDS - Plastic Behavior
Compressive Stresses
"UP" folds are anticlines - beds dip away
from each other
"DOWN" folds are synclines - beds dip
toward each other
The AXIAL PLANE divides the fold into two
equal halves
If the dips are the same the fold is
symmetrical - otherwise asymmetrical