Tenmile and Mosquito Ranges
With scarcely a break, the Park Range-Gore Range structure continues southward into the Tenmile and Mosquito Ranges. These high ridges separate South Park from the upper Arkansas Valley, and include a cluster of very high peaks, Quandary, Mt. Lincoln, Mt. Democrat, and Mt. Bross, all over 14,000 feet in elevation.
Structurally, both the Tenmile Range and the Mosquito Range are highly asymmetrical [anticlines], gentle on the east and steeply faulted on the west. Paleozoic sedimentary rock layers containing many [fossils] cover large portions of the higher parts of these ranges, but two of the highest peaks, Mt. Bross and Mt. Lincoln, are capped by the Lincoln [Porphyry], a Tertiary intrusive, while Quandary Peak is Precambrian [granite].
These mountains are highly mineralized, and have been extensively explored and mined. The Climax Molybdenum Corporation operates an especially large mine at Climax, and the New Jersey Zinc Company has a large underground mine and mill at Gilman, on the western slopes of Tenmile Range.
Buffalo Peaks, two highly eroded volcanic mountains near the south end of Mosquito Range, are extrusions of [lava] and ash which have buried the axis of the Mosquito uplift. They are major volcanoes related to a group of small volcanic cones near Antero Junction, in South Park.
South of Buffalo Peaks, near Trout Creek Pass, the Mosquito Range loses altitude rapidly and merges with the rough country called the Arkansas Hills. Cinder cones, [dikes], and other evidences of Tertiary volcanic activity can be seen between Trout Creek Pass and Salida.