Grand Canyon

36.1069°N, 112.1129°W.

Erosional canyon cut by the Colorado River through northern Arizona over the past 5–6 million years, with maximum dimensions 446 km long, 29 km wide, and 1,857 metres deep. The exposed wall reveals approximately 2 billion years of Earth's geological history in stratigraphic sequence: Vishnu Schist (Precambrian, 1.7 billion years) at the bottom, Kaibab Limestone (Permian, 270 million years) at the rim, with the Great Unconformity in between representing approximately one billion years of missing rock. The canyon is sacred to the Havasupai, Hualapai, Hopi, Navajo, Paiute, and Zuni tribes; the Hopi Sipapuni in the Little Colorado River canyon is the place of emergence in Hopi origin mythology. The canyon was first descended in 1869 by John Wesley Powell with one wooden boat and one prosthetic arm; three of his ten men deserted at Separation Canyon and were killed before they reached settlement.

A canyon that exposes two billion years of Earth's history was first descended by a one-armed geologist who lost three men just before the end.