In the structural geology of major collisional mountain ranges, which of the following terms describes a large-scale, low-angle thrust fault that transports massive sheets of older crystalline basement rocks over younger sedimentary strata for tens of kilometers?

💡 Solution & Explanation

A nappe is a large tectonic sheet or thrust fold that has moved great distances over underlying rocks along a predominantly low-angle fault plane during intense continental collision and crustal shortening. Graben structures are down-faulted block valleys bounded by normal faults. Strike-slip and transform faults involve horizontal lateral displacement along vertical shear planes. Nappes are prominent structural features in the Alps, Himalayas, and Appalachian mountain chains, revealing complex tectonic stacking.