The Grand Staircase is an immense sequence of

sedimentary rock Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particle ...

layers that stretch south from

Bryce Canyon National Park Bryce Canyon National Park () is an American national park located in southwestern Utah. The major feature of the park is Bryce Canyon, which despite its name, is not a canyon, but a collection of giant natural amphitheaters along the eastern ...

and

Grand Staircase–Escalante National Monument The Grand Staircase–Escalante National Monument (GSENM) is a United States national monument protecting the Grand Staircase, the Kaiparowits Plateau, and the Canyons of the Escalante ( Escalante River) in southern Utah. It was established in 1 ...

, through

Zion National Park Zion National Park is an American national park located in southwestern Utah near the town of Springdale. Located at the junction of the Colorado Plateau, Great Basin, and Mojave Desert regions, the park has a unique geography and a variety o ...

, and into

Grand Canyon National Park Grand Canyon National Park, located in northwestern Arizona, is the 15th site in the United States to have been named as a national park. The park's central feature is the Grand Canyon, a gorge of the Colorado River, which is often considered ...

Characterization

In the 1870s, geologist

Clarence Dutton Clarence Edward Dutton (May 15, 1841 – January 4, 1912) was an American geologist and US Army officer. Dutton was born in Wallingford, Connecticut on May 15, 1841. He graduated from Yale College in 1860 and took postgraduate courses there un ...

first conceptualized this region as a huge stairway ascending out of the bottom of the Grand Canyon northward with the cliff edge of each layer forming giant steps. Dutton divided this layer cake of Earth history into five steps from the youngest (uppermost) rocks: * Pink Cliffs *

Grey Cliffs Grey (more common in British English) or gray (more common in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning literally that it is "without color", because it can be composed ...

* White Cliffs * Vermilion Cliffs * Chocolate Cliffs Since then, modern geologists have further divided Dutton's steps into individual rock

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondary ...

s. Formations in the Grand Staircase starting with the youngest (uppermost) rocks: * Claron Formation *

Kaiparowits Formation The Kaiparowits Formation is a sedimentary rock formation found in the Kaiparowits Plateau in Grand Staircase–Escalante National Monument, in the southern part of Utah in the western United States. It is over 2800 feet (850 m) thick, and is Ca ...

Wahweap Formation The Wahweap Formation of the Grand Staircase–Escalante National Monument is a geological formation in southern Utah and northern Arizona, around the Lake Powell region, whose strata date back to the Late Cretaceous (Campanian stage). Dinosaur r ...

* Straight Cliffs Formation * Tropic Shale *

Dakota Sandstone The Dakota is a sedimentary geologic unit name of formation and group rank in Midwestern North America. The Dakota units are generally composed of sandstones, mudstones, clays, and shales deposited in the Mid-Cretaceous opening of the Western Int ...

Carmel Formation The Carmel Formation is a geologic formation in the San Rafael Group that is spread across the U.S. states of Wyoming, Utah, Colorado, north east Arizona and New Mexico. Part of the Colorado Plateau, this formation was laid down in the Middle J ...

* Temple Cap Formation * Navajo Formation *

Kayenta Formation The Kayenta Formation is a geological formation in the Glen Canyon Group that is spread across the Colorado Plateau province of the United States, including northern Arizona, northwest Colorado, Nevada, and Utah. Traditionally has been suggested ...

Moenave Formation The Moenave Formation is a Mesozoic geologic formation, in the Glen Canyon Group. It is found in Utah and Arizona. The Moenave was deposited on an erosion surface on the Chinle Formation following an early Jurassic uplift and unconformity that ...

Chinle Formation The Chinle Formation is an Upper Triassic continental geological formation of fluvial, lacustrine, and palustrine to eolian deposits spread across the U.S. states of Nevada, Utah, northern Arizona, western New Mexico, and western Colorado. In ...

Moenkopi Formation The Moenkopi Formation is a geological formation that is spread across the U.S. states of New Mexico, northern Arizona, Nevada, southeastern California, eastern Utah and western Colorado. This unit is considered to be a group in Arizona. Par ...

Kaibab Limestone 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 Ar ...

Toroweap Formation The Middle Permian Toroweap Formation is a thin, darker geologic unit, between the brighter colored units of the Kaibab Limestone above, and Coconino Sandstone below. It is a prominent unit in Grand Canyon, Arizona, USA, found through sections ...

Coconino Sandstone Coconino Sandstone is a geologic formation named after its exposure in Coconino County, Arizona. This formation spreads across the Colorado Plateau province of the United States, including northern Arizona, northwest Colorado, Nevada, and Utah. ...

* Hermit Shale *

Supai Group The Supai Group is a slope-forming section of red bed deposits found in the Colorado Plateau. The group was laid down during the Pennsylvanian to Lower Permian. Cliff-forming interbeds of sandstone are noticeable throughout the group. The Supai ...

* Surprise Canyon Formation * Redwall Limestone *

Temple Butte Limestone The Devonian Temple Butte Formation, also called Temple Butte Limestone, outcrops through most of the Grand Canyon of Arizona, USA; it also occurs in southeast Nevada. Within the eastern Grand Canyon, it consists of thin, discontinuous and rela ...

Muav Limestone The Cambrian Muav Limestone is a geologic unit within the 5-member Tonto Group. It is about thick at its maximum. It is a resistant cliff-forming unit. The Muav consists of dark to light-gray, brown, and orange red limestone with dolomite and ...

Bright Angel Shale The Cambrian Bright Angel Shale is the middle layer of the three member Tonto Group geologic feature. The 3-rock Tonto section famously sits upon the Great Unconformity because of the highly resistant cliffs of the base layer, vertical Tapeats S ...

* Tapeats Sandstone

Geology

The major sedimentary rock units exposed in the Grand Canyon range in age from 200 million to 600 million years and were deposited in warm shallow seas and near-shore environments. The nearly 40 identified rock layers of Grand Canyon form one of the most studied geologic columns in the world. The oldest exposed formation in Zion National Park is the youngest exposed formation in the Grand Canyon – the ~240‑million-year-old

. The Bryce Canyon area to the northeast continues where the Zion area leaves off by presenting

Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configu ...

-aged rocks that are 100 million years younger. In fact the youngest formation seen in the Zion area is the oldest exposed formation in Bryce Canyon – the

. There are, however, shared rock units between all three, creating a super-sequence of

s that geologists call the Grand Staircase. Bryce Canyon's formations are the youngest known units in the Grand Staircase. Younger rock units, if they ever existed, have been removed by

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is di ...

. These layers have undergone 5000 to 10,000 feet (1500 to 3000 m) of uplift starting about 66 million years ago with the

Laramide orogeny The Laramide orogeny was a time period of mountain building in western North America, which started in the Late Cretaceous, 70 to 80 million years ago, and ended 35 to 55 million years ago. The exact duration and ages of beginning and end of the o ...

which has increased the ability of the

Colorado River The Colorado River ( es, Río Colorado) is one of the principal rivers (along with the Rio Grande) in the Southwestern United States and northern Mexico. The river drains an expansive, arid watershed that encompasses parts of seven U.S. s ...

to cut its channel to make individual plateaus out of the

Colorado Plateau The Colorado Plateau, also known as the Colorado Plateau Province, is a physiographic and desert region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. This province covers an area ...

s region. The major canyons of the region did not start to form until about five to six million years ago when the

Gulf of California The Gulf of California ( es, Golfo de California), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Bermejo''), is a marginal sea of the Pacific Ocean that separates the Baja C ...

opened up and thus lowered the river's

base level In geology and geomorphology a base level is the lower limit for an erosion process. The modern term was introduced by John Wesley Powell in 1875. The term was subsequently appropriated by William Morris Davis who used it in his cycle of erosi ...

(its lowest point).

Paleontology

In the 1880s, many large

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

skeletons were excavated from southern

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...

in regions north of the Grand Staircase. Following these discoveries there was little interest in further exploration. In the late 20th and early 21st centuries there has been greatly renewed interests in the strata of the Grand Staircase, particularly since the exposure and collection of new fossils in previously unexplored strata has a high probability of revealing fossil remnants of hitherto unseen

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

. Southern Utah has continued to reward researchers owing to its climatological "sweet spot" for exposing fossil remnants for observation and collection at the surface. At locations south, in Arizona, the climate is so dry that erosion is relatively slow. Further north, the wetter climates encourage growth of forests, which destroy fossils by the actions of roots and soil bacteria. In southern Utah, there are enough strong and wet storms to cause episodic rapid erosion and the consequent exposure of fossil remains, but with insufficient annual average rainfall to support destructive, deep-rooted plant life.

Gallery

(South to north, climbing the staircase) Image:Vermilioncliffsglencanyon.jpg, Vermilion Cliffs Image:Navajo SS-Escalante.jpg, White Cliffs Image:SEUtahStrat.JPG, The Permian through Jurassic part of the staircase, as seen at

Glen Canyon NRA Glen Canyon National Recreation Area (shortened to Glen Canyon NRA or GCNRA) is a national recreation area and conservation unit of the United States National Park Service that encompasses the area around Lake Powell and lower Cataract Cany ...

References

*''The Salt Lake Tribune'', May 21, 2006, p. 1: A New Golden Age – "Utah's peak for dinosaur discoveries ended in the 1920s but recent finds have the state on the cusp of another boom"
National Park Service: Bryce Canyon National Park Nature and Geology – The Grand Staircase
(public domain text). Not found 4/8/08

Official Website for the Bureau of Land Management Grand Staircase-Escalante National Monument

External links