Laramide orogeny

Magmatism associated with subduction occurred not near the plate edges (as in the volcanic arc of the Andes, for example), but far to the east, along the Colorado Mineral Belt.

This style of deformation is typical of continental plates adjacent to convergent margins of long duration that have not sustained continent/continent collisions.

Since the Oligocene, episodic epeirogenic uplift gradually raised the entire region, including the Great Plains, to present elevations.

Most of the modern topography is the result of Pliocene and Pleistocene events, including additional uplift, glaciation of the high country, and denudation and dissection of older Cenozoic surfaces in the basin by fluvial processes.

Most bounding faults show evidence of at least two episodes of Laramide (Late Cretaceous and Eocene) movement, suggesting both thrust and strike-slip types of displacement.

[4] According to paleontologist Thomas M. Lehman, the Laramide orogeny triggered "the most dramatic event that affected Late Cretaceous dinosaur communities in North America prior to their extinction.

"[5] This turnover event saw the replacement of specialized and highly ornamented centrosaurine and lambeosaurines by more basal upland dinosaurs in the south, while northern biomes became dominated by Triceratops with a greatly reduced hadrosaur community.