Never Summer Mountains - Geology

Geology

The rocks of Never Summer Mountains are younger than most of the surrounding mountain ranges. They, along with the Rabbit Ears Range to the west, were formed by volcanic and intrusive processes 24-29 million years ago and consist mostly of igneous granitic formations along with preceding metamorphic formations. Most of the highest peaks in the range are granodiorite that was uplifted during the Miocene epoch. The range's highest summit, Mount Richthofen, is the remnant of an andesite volcanic plug. The Nokhu Crags in the north are mostly Pierre Shale dating from Cretaceous times. A large thrust fault underneath the Kawuneeche Valley thrust older Precambrian rocks on top of the younger Cretaceous rocks on the east side of the range. The southern peaks are Miocene-aged granite, and finally Precambrian-aged biotite gneiss and schist.

Beginning two-million years ago glaciers began carving the jagged peaks of the Never Summer Mountains. Successive waves of glaciation continued to reshape the mountains until the Pinedale Glaciation ended twelve-thousand years ago.

The peaks are enormous weathered masses of granitic rock heavily covered with green and orange lichens surrounded on all sides by large fields of talus shed from the original peaks. Many alpine lakes are nestled amongst the peaks. Most vegetation is low-growing and stunted. Few trees grow at the higher altitudes and Krummholz abounds.