AGE: 1.2 billion years
(Precambrian Era)

THICKNESS: Varies; several hundred feet

COMPOSITION: Primarily sandstone

NOTES: The distinctive tilted strata of the Grand Canyon Supergroup appear only intermittently in the western part of the canyon. The Supergroup is a prominent feature, however, from Red Canyon eastward; in that part of the canyon its thickness is like that of the Vishnu schist in the west.