The Hakatai Shale
is a Mesoproterozoic rock formation
that outcrops in the Grand Canyon
, Coconino County, Arizona
. It consists of colorful strata
that exhibit colors that vary from purple to red to brilliant orange on outcrop. The colors are the result of the oxidation
of iron-bearing minerals in the Hakatai Shale. It consists of lower and middle members that consist of bright-red, slope-forming, highly fractured, argillaceous mudstones
and an upper member composed of purple and red, cliff-forming, medium-grained sandstone
. Its thickness, which apparently increases eastwards, varies form 137 to 300 m (449 to 984 ft). In general, the Hakatai Shale and associated strata of the Unkar Group
northeast (10°-30°) toward normal faults
that dip 60° or more toward the southwest. This can be seen at the Palisades fault in the eastern part of the main Unkar Group outcrop area (below East Rim). In addition, thick, prominent, and dark-colored basaltic sills
cut across the purple to red to brilliant orange strata of the Hakatai Shale.
The bright orange-red slopes of the Hakatai Shale contrasts sharply against the grayish outcrops of the Bass Formation. The outcrop of the Hakatai Shale also contrasts greatly with the steep cliffs formed by Shinumo Quartzite as seen at the base of Isis Temple
. In the central Grand Canyon north of Grand Canyon Village and viewed from the south at the South Rim, the bright orange-red unit can be seen below the Isis Temple and Cheops Pyramid landforms at the intersection of Bright Angel Canyon and Granite Gorge; the Bright Angel Trail from the South Rim traverses through the geographic region to the north, the North Kaibab Trail
in Bright Angel Canyon. Read more...