resulting structure is called a monocline. If both limbs are compressed, and are equally inclined to the horizontal, the fold is called an isocline.
In great mountain ranges, such as the Alps, the lateral compression is very great, and the folds are crushed in at the base, forcing the axes to splay out fan fashion. Fan structure, or the collection of a number of folds in
Fig. 26.—Fan-structure in Mountains; the strata have been folded with the axes of the folds splaying out fan fashion. Notice that going up the hill the normal succession is first observed, the lowermost bed being at the bottom and the next succeeding above; further up the order is reversed. The dotted portions of the folds have been removed by denudation. In the outer portions of the folds the beds have been strongly over-folded. Types: Alps and Himalayas.
an arched composite fold, is called an anticlinorium, whereas when they are collected into a trough the whole is called a synclinorium. A portion of fold in being bent may become crinkled with innumerable small bends. These are so frequent in the great folded mountains of the south coast of South Africa that they may almost be said to be characteristic of them. Gorgeous sections showing this crinkling are exhibited in all stages in Meiring's Poort, Oudtshoorn, but similar folds may be seen along the railway in the Alicedale Poort, on the Midland line. Sometimes the crinkles may be even
