Fold (geology) - Describing Folds - Fold Tightness

Fold Tightness

Fold tightness is defined by the angle between the fold's limbs, called the interlimb angle. Gentle folds have an interlimb angle of between 180° and 120°, open folds range from 120° to 70°, close folds from 70° to 30°, and tight folds from 30° to 0°. Isoclines, or isoclinal folds, have an interlimb angle of between 10° and zero, with essentially parallel limbs.

Read more about this topic:  Fold (geology), Describing Folds