Kaibab Limestone

Kaibab Limestone Stratigraphic range: Early to Middle Permian, Leonardian to Roadian
Bedded and jointed cliffs of the Kaibab Limestone at the Grand Canyon. (high resolution, expandable photo)
Type	Geological formation
Sub-units	Fossil Mountain and Harrisburg members
Underlies	Moenkopi Formation
Overlies	Toroweap Formation, Coconino Sandstone, and White Rim Sandstone
Thickness	300 feet (91 m)-500 feet (150 m) in Grand Canyon region.
Lithology
Primary	fossiliferous limestone, sandy limestone, dolostone, and chert
Other	gypsum, siltstone, and sandstone
Location
Region	Northern Arizona, southeast California, east-central Nevada, and southern Utah
Country	United States of America
Type section
Named for	It was named for the Kaibab Plateau, northern Arizona
Named by	Darton (1910)

The Kaibab Limestone is a resistant cliff-forming, Permian geologic formation that crops out across the U.S. states of northern Arizona, southern Utah, east central Nevada and southeast California. It is also known as the Kaibab Formation in Arizona, Nevada, and Utah. The Kaibab Limestone forms the rim of the Grand Canyon. In the Big Maria Mountains, California, the Kaibab Limestone is highly metamorphosed and known as the Kaibab Marble.

The Kaibab Limestone was named by Darton in 1910 for the Kaibab Plateau, which is on the north side of Grand Canyon in Coconino County, Arizona. In his definition of the Kaibab Limestone formation, no type locality was designated. He also designated the Kaibab Limestone as the upper formation of the Aubrey Group, a now-abandoned stratigraphic unit. In 1921, Bassler and Reeside revised Darton's work and defined the Harrisburg Member of the Kaibab Limestone. In his 1938 monograph on the Toroweap Formation and Kaibab Limestone of northern Arizona, McKee split Darton's original Kaibab Limestone into the currently recognized Kaibab Limestone and Toroweap Formation. He also revised Kaibab Limestone's lower contact and divided it into informal (descending) alpha, beta and gamma members. Later in the 1970s, its upper contact was revised and its aerial extent were defined. Also, unsuccessful attempts were made to raise the formation to group rank and divide it into several formations. In 1982, Warren Hamilton renamed it as the Kaibab Marble and determined its areal extent for California. In 1991, Sorauf and Billingsley subdivided the Kaibab Limestone into (ascending) Fossil Mountain Member (new) and Harrisburg Member. They designated the strata comprising McKee's alpha (or upper) member as the Harrisburg Member and the strata comprising McKee's beta (or middle) member as the Fossil Mountain Member. The Fossil Mountain Member was named for Fossil Mountain along the south rim near the Bass Trail. McKee's gamma member is considered to be part of the Fossil Mountain Member. Later research has further redefined the regional extent of the Kaibab Limestone.