what is the differenece between a fault and a joint?

Answer 1

Both are fractures. Joints are fractures without displacement, faults are fractures with displacement of strata either vertically or horizontally. Devil's Tower is an example of jointing.

Answer 2

A joint is a generally planar fracture formed in a rock as a result of extensional stress. Joints are distinct from faults because joints do not have any significant offset of strata either vertically or horizontally.So joint is the plane where two blocks have a least displacement.

Geologic faults, fault lines or simply faults are planar rock fractures, which show evidence of relative movement. Large faults within the Earth's crust are the result of shear motion and active fault zones are the causal locations of most earthquakes.

Answer 3

From the Dictionary of Geological Terms:

fault--A fracture or fracture zone along which there has been displacement of the sides relative to on another parallel to the fracture.

joint--A surface of fracture or parting in a rock, without displacement; the surface is often plane and may occur with parallel joints to form a joint set.

From Geology Today (college text book)

Joints--Because of the weight of overlying rock, rock masses buried deep beneath the Earth's surface are under enormous stress. As erosion wears down the surface, the weight of the overlying rock, and hence the confining stress, are reduced. The rock responds by expanding. As it does so, fractures typically develop: these are called joints. These are fractures in a rock along which no appreciable movement has occurred. Joints are a type of brittle deformation. They are different from faults because the blocks on either side have not moved very far relative to each other along the fracture.