A thrust is like a reversed fault in that it is the result of compression and that the inclination or hade of the fault is toward the upthrow side, which is the hanging wall, but differs in the tendency to a horizontal position of the plane of fracture and in the association with violent folding and plications. In his latest work on the subject Mr. Willis divides thrusts into the following three groups: I. Scission-thrusts are those in which the fault-plane is independent of any older structures, and occur chiefly in the crystalline schists (metamorphic rocks) and granite, and, as a rule, depart but little from horizontality. Thrusts of this kind are developed on a great scale in the southern Appalachians, especially in eastern Tennessee, where thrusts of 20 miles or more have been observed. On an even more gigantic scale they occur in the Highlands of Scotland and Norway, where the movement of translation amounts to 75 miles.

Fold thrust, near Highgate Springs, Vt. (U. S. G. S).

Fig. 183. - Fold thrust, near Highgate Springs, Vt. (U. S. G. S).