Definition of rift

i. A regional-scale strike-slip fault, e.g., the San Andreas rift in California, with offset measured in hundreds of kilometers.

Ref: AGI

ii. A trough or valley formed by faulting.

iii. In quarrying, a direction of parting in a massive rock, such as granite, at approx. right angles to the grain.

Compare with: grain, hard way

Ref: AGI

iv. A narrow cleft, fissure, or other opening in rock (such as in limestone), made by cracking or splitting.

Ref: AGI

v. A planar property whereby granitic rocks split relatively easily in a direction other than the sheeting (parallel to the surface of the Earth.)

Ref: AGI

vi. A term used in slate quarrying to describe a second direction of splitting less pronounced than slaty cleavage and usually at right angles to it.

vii. In sedimentary rocks, the horizontal plane of stratification, or the bed of the rock.

Ref: Stauffer

viii. An obscure foliation, either vertical (or nearly so) or horizontal, along which a rock splits more readily than in any other direction.

Synonym of: fault trace

ix. A crack, such as in the mid-ocean ridges.

Ref: MacCracken