Tags: Mountain Range.
The Lewis Range is a mountain range located in the Rocky Mountains of northern Montana U.S. and extreme southern Alberta Canada. Formed by the Lewis Overthrust beginning 170 million years ago an enormous slab of Precambrian rocks 3 miles (4.8 km) thick 50 miles (80 km) wide and 160 miles (260 km) long faulted and slid over newer rocks of the Cretaceous period. In this relatively rare occurrence older rocks are now positioned above newer ones.
