STRESS, FAULTS, AND FOLDS Flashcards
is the bending, tilting, and breaking of the Earth’s crust. Plate tectonics is the major cause of crustal deformation.
Deformation
Thicker and heavier crust sink deeper into the mantle where thinner and lighter crust will rise higher on the mantle.
Isostasy is the rising or settling of a portion of the Earth’s lithosphere that occurs when weight is removed or added in order to maintain equilibrium between buoyancy forces that push the lithosphere upward and gravity forces that pull the lithosphere downward.
Equal stand still
Isostasy
The up and down movement of the crust to reach isostasy. During this adjustment the rocks in the crust are bent causing deformation.
Isostatic adjustment
There are 3 basic kinds of stress that the isostatic adjustment causes
Compression, Tension, Shearing
occurs when crustal rocks are squeezed together.
Compression
occurs when crustal rocks are squeezed together.
Compression
the force that pulls rocks apart. Here rocks tend to become thinner.
Tension
pushes rocks in opposite directions. rocks bend, twist and break.
Shearing
The result of stress are
Folding and faulting.
When a rock has stress put on it and does not break it is called. appear as wave-like structures in rock layers. Some are small and can be seen in individual rocks and some folds are huge and can only be seen from the air.
Folding
The 3 general types of folds
Anticlines
Synclines
Monocline
Rocks don’t always bend, sometimes they break. When the rock moves and breaks it is called
Fault
The side that is above the fault plane is called the
Hanging wall
When the hanging wall moves down it is called. occur in places where there is tension or the rocks are being pulled apart.
Normal fault
When the hanging wall moves up it is called. are caused by compressional forces.
Reverse fault
A low angle reverse fault is called a because one side is being thrust onto the other.
Thrust fault
faults slide horizontally past one another.
Strike-slip fault
If you are looking across to the other side of a strike-slip fault and that side moves to the left of you it is called a left lateral strike-slip fault. Strike-slip faults occur in and around transform plate boundaries like where we live near the San Andreas fault. This is also where shearing takes place.
