Oldhorn Mountain is a 3,000-metre peak in Alberta's Jasper National Park, in the Trident Range of the Canadian Rockies. Named in 1916 by William Pittman Hinton for its hornlike shape, it was officially adopted in 1935 and first climbed in 1924 by Lawrence Coolidge, George Higginson, Joe Johnson, and guide Alfred Streich. The mountain rises steeply above the Astoria River, and runoff drains south into that valley. Its south slope supports slow-moving rock glaciers formed from talus and interstitial ice. Geologically, Oldhorn consists of ancient sedimentary rock, with Gog quartzite over Miette Group shale, shaped by the Laramide orogeny.