More folds and faulted folds

Abstract

In the folds so far studied, the axis of the fold has been horizontal. The axis is the intersection of the axial plane with any bedding plane. (Make a synclinal fold by taking a piece of paper and folding it in two to make a simple V-shape. Drop a pencil into this and it will assume the position of the axis

of the fold.) Such a fold, with the axis horizontal, is called a non-plunging fold. The outcrops of the limbs tend to be parallel (but of course are affected by the configuration of the ground) since the structure contours drawn on one limb are parallel to those drawn on the other limb. (They have, as well, been parallel to the axial plane and, in cases where the axial plane was vertical, parallel to the axial trace ( = outcrop of the axial plane).)