Volcanism

A common dating tool used by geologists and paleoecologists is the dating of ash layers deposited by volcanic eruptions. Ash horizons in soils and rocks can be radiocarbon-dated to help constrain the age of events that occurred both before and after deposition of the layer.  

Though vast areas of the Colorado Plateau are composed of sedimentary rocks which give the Plateau its distinctive landscape, there are a few areas of volcanic activity. The Markagunt Plateau and the Sevier Plateau in Utah, the Hopi Buttes, White Mountains, San Francisco Peaks, and Uinkaret Mountains (Mt. Trumbull) in Arizona, and the Jemez Mountains and Mt. Taylor in New Mexico are all volcanic in origin.

Breed, W. J. 1989. Molten rock and trembling earth: The story of a landscape evolving. Plateau 49: 2-13.

Colton, H. S. 1947. A revised date for Sunset Crater Volcano. Geological Review 37: 144.

Hevly, R. H., Kelly, R. E., Anderson, G. A. and Olsen, S. J. 1979. Comparative effects of climate change, cultural impact, and volcanism in the paleoecology of Flagstaff, Arizona, A.D. 900-1300. Pp. 487-523 In: Sheets, P. D. and Grayson, D. K., editors. Volcanic activity and human ecology. Academic Press, New York.

Masura, J. E. 1998. Stratigraphy and sedimentology of the Upper Jurassic Brushy Basin Member of the Morrison Formation near Tidwell Wash, Emery County, Utah, and description of the depositional environment. Masters Thesis. Washington State University, Pullman.

Smith, E. I., Sanchez, A., Walker, J. D. and Wang, K. 1999. Geochemistry of mafic magmas in the Hurricane volcanic field, Utah: Implications for small- and large-scale chemical variability of the lithospheric mantle. Journal of Geology 107: 433-448.