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A planar or subplanar surface of shear which displaces the strata or rocks on either side of it parallel to the plane.

E. Determination of fault displacement

1. Complete determination using piercing points

2. Partial determination from small?scale structures

a) Slickenfiber lineations

b) Secondary fractures

c) S-C foliations

d) Shear folding (sheath folding)

e) Asymmetric porphyroclasts

f) Rotated inclusion trails in porphyroblasts

g) Fractured porphyroclasts


1. Features intrinsic to faults

a) Fault rocks features

b) Secondary features

2. Effects of faulting on geologic or stratigraphic units

a) Repetition & omission of strata

b) Drag folds

(1) When strat cutoff lines are at a high angle to slip

(2) Don't form when cutoff lines are at a low angle to slip

3. Physiographic criteria for faulting

a) Fault scarp - continuous linear breaks in slope that result directly from displacement of topography

b) Flatirons - erosional remnants of fault scarp

c) Fault line scarps - erosional features that are characteristic of both active and inactive faults

Fault breccia, fault drag, extension fissures, slickensides, mineralization and silica enrichment, pseudotachylyte, gouge etc.