Horseshoe Mountain is a 13,905-foot summit in Colorado’s Mosquito Range of the Rocky Mountains, about 7.1 miles southeast by east of Leadville. Set on a drainage divide that also forms county and national forest boundaries, it is especially notable for the striking cirque that gives the mountain its name. This bowl-like feature was carved into Paleozoic sedimentary rocks originally deposited in ancient seas. Unlike many high Colorado peaks, where ice age glaciers removed such layers, glaciation here shaped the mountain into a prominent horseshoe without stripping the sedimentary rock away. That rare survival makes it both a high alpine peak and an important geologic landmark.