The "Grand Sentinel" is the largest of several pillars or pinnacles located on the mountain. It is found part way up the slopes leading from Paradise Valley to Sentinel Pass and rises 120 metres from the scree slope. Its longest face is about 300 metres high. Samuel Allen originally named this peak Sentinel Mountain. Pinnacle Mountain is well known for its "rotten" rock and three previous attempts had been unsuccessful before Edward Feuz jr. and Rudolph Aemmer led J.W.A. Hickson to its summit in 1909.