FOLDS & FAULTS

Words to know Rock Strata

These are rock layers under the surface. They are normally flat (horizontal) when

deposited. Fold Fault Stratigrapher

Geologist that studies rock layers. Rebound theory

Normal Strata Flat - aka Horizontal

Irregular strata Sometimes rock strata is squeezed

and “folded” A fold is when the strata is bent.

Folded Strata How does flat strata become folded?

Compressional forces bend the strata. Like paper would respond if you push the sides

together

Large scale folding

Faulted Strata

What causes strata to fault or break? Fault is when the strata breaks from

outside forces.

Rebounding theory Think of a rubber band. If I hold it out it will be flat. But if I add weight it will dip down But when I take the weight off it goes

back. The Earth does the same! When Earth sinks then bounces back

from large masses.

Measuring Folds & Faults Strike

The strike is a line the shows the directions on the surface of the fault.

Dip The angle the plane

goes into the ground.

Types of faults

1.)Normal 2.)Reverse (thrust)3.)Strike Slip

Faults are caused from forces within the Earth pushing or pulling rock strata.

How to ID Faults

Head Wall Foot Wall

Normal Fault Head wall moves down

Reverse Fault Head wall moves up

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Strike Slip