Volcanic Petrology

With a Geological Twist

Shoshone Volcanics

Absaroka Volcanic Field

Volcanic activity occurs in local areas and endures for limited periods of geologic time.

The Eocene Absaroka Volcanic Field (Smedes and Prostka, 1972) formed in northwestern Wyoming over a 5 million year span. The Absaroka Volcanic Field is the largest of several Eocene fields that formed in the Northern Rocky Mountains. The Absaroka Field covers some 23,000 km². The volume of the rock exceeds 29,000 cubic kilometers. Most of the rocks in the Absaroka Field are either lava flows, parts of stratovolcanoes, or volcaniclastic sediments shed from the slopes of the volcanoes. Uplift and erosion have exposed the rocks in spectacular cliffs and mountain peaks. The photograph shows some of the lava flows near the south end of the field.

Absaroka Lava Flows, Wyoming

Volcanic Petrology

These web pages on Volcanic Petrology provide you access to the theory and tools for interpreting depths and temperatures of processes that produced volcanic rocks we see at the surface of the Earth and other planets. The first set of pages provides the theoretical background; the second set of pages provides a look at several case studies; the third set of pages gives you access to computer programs for making various calculations; and the last set of pages outlines lab exercises involving suites of volcanic rocks. You can reach these several sets of web pages by clicking on the links to the left.

On the pages of the web site are photographs of volcanic landforms, volcanic features, and volcanic rocks. If you click on the photographs, an explanation of what you are looking at will appear. Some questions, often related to unsolved problems associated with the features, accompany many of the descriptions. Please feel free to comment by clicking the e-mail link at the bottom of the description.