Research Paper on:
North America's Ignimbrite Formations

Unformatted Sample Text from the Research Paper:
the Western portion of the United States, as well as in other regions around the world. These formations are the result of volcanic eruptions and through time have created some  incredibly intriguing sites for research. In the following paper we provide a description and discussion of the Mid Tertiary Ignimbrite flare-up, discussing Mt. St. Helens eruption as well. The paper  then examines three other spots in the Western United States which demonstrate evidence of Ignimbrite formations. The areas discussed are the Pelen/McCoy region/mountains of California, the Sierra Nevada area of  California, and Church Rock, Arizona. Mid-Tertiary Ignimbrite Flare-Up "A period of explosive volcanism rocked the western United States approximately 25-40 million years ago (Armstrong and Ward, 1991), producing  hot ash flows and volcanic deposits that covered parts of the region. This event, termed the Mid-Tertiary Ignimbrite Flare-up, erupted a truly voluminous amount of igneous material, perhaps over 120,000  cubic miles of rock (Johnson, 1991)!!" (Cannon, 2002). Another author indicates that "The mid-Tertiary Ignimbrite flare-up is just one of several geologic and tectonic events that has taken place in  the Cordilleran during Cenozoic time" (2. Geologic Background - The Mid-Tertiary Ignimbrite Flare-Up, 2002). By the late Cretaceous period "the western United States had experienced accretion of terranes in  the Proterozoic and Phanerozoic, at least two Phanerozoic orogenies (Antler, Sonoma), and the development of a subduction zone along the western margin in the Mesozoic (Odlow et al., 1989). In  the late Cretaceous, thin-skinned deformation from the Sevier Orogeny resulted in east transport of thrust sheets across the Cordilleran region (Odlow et al., 1989)" (2. Geologic Background - The Mid-Tertiary  Ignimbrite Flare-Up, 2002). Occurring at approximately the same time "was the Laramide Orogeny in the late Cretaceous and early Tertiary. The Laramide orogeny consisted of thick-skinned deformation involving possible reactivation