Page:South African Geology - Schwarz - 1912.djvu/105

 fold is called the crest of the syncline or anticline, the two sides are called the limbs of the fold, and a straight line equally dividing the two limbs is called the axis of the fold. The limbs are said to dip at a certain angle to the north, south, east, or west, and so forth, the angle

being reckoned from the horizontal. The axis of the fold also dips at a given angle, but the extension of the axis right and left, measured along a horizontal plane, is called the strike of the fold. The fold consists of layers of rocks of considerable extent, and the fold

is greatest where the horizontal thrust is largest; at either side the thrust is not so great, the consequent folding is not so intense, and at a certain distance from the centre the fold gradually dies out. There is then a longitudinal dip as well as a transverse dip, and the fold is said to pitch along its line of strike. An