Black Mesa

Black Mesa Image

Black Mesa [Dzilyíjiin] is the dominant landscape feature over much of this area. It is a large structure of the least eroded, and therefore the youngest, soil in this area. It is capped by Mesa Verde sandstone which lies above much softer layers. Working down from the top, these are a layer of very soft Mancos shale, the Morrison Formation, Dakota sandstone and the San Rafeal group. The lower layers are being constantly eroded wher they are exposed on the sides of the mesa, leading to landslides and constant valley widening.

The Mancos Shale is the product of a Cretaceous era sea and contains fossils of marine shellfish such as ammonites and the skeletons of fish (including sharks), crocodiles, turtles and even pleiosaurs. The lagoon deposits are near the surface over most of the mesa and are the source of most of the coal that is currently being strip mined. In this process, the vegetation is removed, the top soil pushed aside, and the "overburden" ( as much as 180 feet!) is stripped away to get at the coal. Huge power shovels remove the coal which is crushed and carried by conveyor belt, slurry pipeline and railroad to power plants, such as those at Page and even in Nevada. Approximately 12 million tons of coal are mined annually. While royalties are paid to the Navajo and Hopi tribes, these royalties are paid at a rate determined 40 years ago and never adjusted. The royalties are currently less than 3% of the price received by Peabody Coal. The mining and transportation of this coal is also a serious drain on the water supply of the Hopi and Navajo tribes. The water table has been drastically lowered due to the mining. This is another issue to be renegotiated with Peabody Coal in the near future.

If you wish to learn more about the Geologic Time Scale or phylogeny (the relationships between groups of organisms as expressed as ancestor/decendent relationships), make use of these links to the Berkeley Museum of Paleontology Web Server. They also have a Dinosaur Hall with an extra special set of pages on the Dilophosaur a new dinosaur (1942) found in the Kayenta Formation on the Navajo Reservation near Tuba City.
If, like me, you are confused by the terms used to designate geologic time, a chart, based upon one given in Roadside Geology of Arizona by H. Chronic is available.

In Association with


Navajo Sacred Places, Klara Bonsack Kelley, Harris Francis, Indiana Univ Press.
Native Roads : The Complete Motoring Guide to the Navajo and Hopi Nations,
Fran Kosik, George Hardeen, Creative Solutions Pub.
Named in Stone and Sky : An Arizona Anthology, Gregory McNamee (Editor),
Univ of Arizona Press.
Talking to the Ground : One Family's Journey on Horseback Across the Sacred Land of the Navajo
Douglas Preston, Univ of New Mexico Press.
A Guide Book to Highway 66, Jack D. Rittenhouse, Univ of New Mexico Press.
Basin and Range, John McPhee, Noonday Press.
Navajo Country : A Geology and Natural History of the Four Corners Region, Donald Baars, Univ. New Mexico Press.
The Colorado Plateau : A Geologic History, Donald L. Baars, Univ of New Mexico Press.
Roadside Geology of Arizona, Halka Chronic, Mountain Press.

In Association with

© 1994 Karen M. Strom

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