Ring Mountain, a flow-dominated tuya in the Mount Cayley volcanic field. It is a nearly circular feature, with a large re-entrant on the southwestern side, and consist of a sequence of glassy, plagioclase-orthopyroxene-phyric andesite flows. The uppermost, horizontal flows are subaerial; they are coarsely jointed and are separated by layers of oxidized scoria. On Ring Mountain's western side, outcrops contain highly variable, fine-scale jointing and are locally broken down into many small spires and knobs. The age is unknown, but lack of evidence for glacial overriding and preservation of finely-jointed, glassy lavas suggests that it may have formed during the Fraser Glaciation (10,000-12,000 years ago).