Coconino Sandstone

The Coconino Sandstone is a geologic formation composed of light-colored quartz arenite of eolian origin. It erodes to form conspicuous, sheer cliffs in the upper walls of Grand Canyon, as part of the Mogollon Rim to the south and east, and in many other parts of the Colorado Plateau region. The Coconino Sandstone is well known for its fossil trackways of terrestrial invertebrates and vertebrates and large-scale cross-stratification.

Eastward of a north–south line from Monument Creek to Fossil Creek, the Coconino Sandstone overlies and interfingers with and grades into the Schnebly Hill Formation, which is equivalent in part to the De Chelly Sandstone in Utah. In this area, it underlies the Kaibab Limestone. Further eastward, the Coconino Sandstone likely correlates with and is contemporaneous with the Glorieta Sandstone of New Mexico. Westward of this line, the upper part of Coconino Sandstone is known as the White Rim Sandstone in Utah and the Cave Springs Member in Arizona. It interfingers and merges westward into the Toroweap Formation. The remaining lower part of the Coconino Formation is known as the Harding Point Member and underlies the Toroweap Formation and uncomfortablyy overlies the Hermit Formation. Between the Toroweap and Hermit formations, the Harding Point Member thins westward until it disappears.