In geology, what are nappe formations?

Question

Hint:

1. Paleozoic Era = 543 million years ago (starting with the Cambrian period - shellfish, trilobites)
2. Mesozoic Era = 248 million years ago (starting with the Triassic period - dinosaurs, mammals)
3. _______ Era = 65 million years ago (starting with the Tertiary period - mass extinction)

Answer 1

A complex fold system of shifted sheets of rock
Encyclopaedia Britannica: "(A) nappe, in geology, (is a) large body or sheet of rock that has been moved a distance of about 2 km (1.2 miles) or more from its original position by faulting or folding. A nappe may be the hanging wall of a low-angle thrust fault (a fracture in the rocks of the Earth’s crust caused by contraction), or it may be a large recumbent fold (i.e., an undulation in the stratified rocks of the Earth’s crust having an essentially horizontal axial plane); both processes position older rocks over younger rocks." The Geological Society in the UK describes the theory of tectonic nappes as "the principle that under compressive stresses, packages of rock can be folded and deformed to the point that they become disconnected from their origins. Tectonic nappes are now considered to be a fundamental mechanism in mountain growth". Examples of cover-rock nappes are in the western Swiss Alps, the Glarus Thrust in eastern Switzerland, the Limestone Alps of Austria, and the nappes above the Johnnie Thrust in Nevada.