Brown Mountain is a small volcanic peak in southern Oregon’s Cascade Volcanic Arc, near Mount McLoughlin. A cinder cone atop a shield volcano, it was formed roughly 12,000 to 60,000 years ago, despite its bare summit giving it a younger appearance. Glacial valleys and a cirque near the top reveal its greater age, while a major eruption about 2,000 years ago spread thick basaltic-andesite aa lava across much of its north and west flanks. Over time it has produced more than 1.2 cubic miles of lava. Its forested lower slopes and sparse upper slopes make it a distinctive record of Oregon’s volcanic and glacial history.