Introduction

The formation of the Rocky Mountains, often referred to as the Laramide orogeny, has been one of the most debated issues in geology. The Rockies form a massive mountain range that stretches from Canada through central New Mexico. The Rocky Mountains formed during a period of intense plate tectonic activity that formed much of the western United States.

The geologic processes that build mountains are normally associated with the subduction of an oceanic plate beneath a continental plate, leading to the formation of a volcanic arc. In the western United States, the subduction of the Farallon plate underneath the North American plate

Most orogenic systems form between 200 to 400 miles inland from a subduction zone boundary. The Rocky Mountains, however are hundreds of miles farther inland. How did this orogeny form so far from the subduction zone? The answer is complex, but appears to lie in the unusual nature of the subducting slab.


On to Geology: Geologic Setting