Pic of the day #32

Pic src: Earth structure – An introduction to structural geology and tectonics

Fold vergence, clockwise (a) and counterclockwise (b), is defined by the apparent rotation of the axial surface from a hypothetical symmetric fold into the observed asymmetric fold, without changing the orientation of the enveloping surface.
In a given geographic coordinate system we may also say east-verging (a) and west-verging (b) folds for clockwise and counterclockwise folds, respectively. In all descriptions we are looking down the plunge of the fold.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.