The Front Range was created by the Laramide Orogeny, the last of three major mountain-building events, which occurred between 70 and 40 million years ago. Tectonic activity during the Cenozoic Era changed the Ancestral Rocky Mountains via block uplift, eventually forming the Rocky Mountains as they exist today. The geologic make-up of Rollins Pass and the surrounding areas were also affected by deformation and erosion during the Cenozoic Era. Many sedimentary rocks from the Paleozoic and Mesozoic eras exist in the basins surrounding the pass.