Elephant Tusk is a prominent 5,254-foot summit in the Chisos Mountains of far West Texas, within Big Bend National Park in the Chihuahuan Desert. An isolated rhyolite intrusion formed about 29 million years ago during the Oligocene, it stands out sharply above the surrounding desert because of its steep profile and striking local relief. The mountain rises 1,950 feet above nearby terrain in just half a mile, in a hot arid climate where limited runoff eventually drains toward the Rio Grande. Its present name was officially adopted in 1939, replacing the earlier map name Indianola Peak, which appeared by 1905.