Geology of Yellowstone

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It is believed that Native Americans inhabited the lands of what is now Yellowstone National Park for more than 11,000 years, until approximately 200 years ago, when European settlers began to drive many of them from their homelands. In 1872 Yellowstone was declared the world’s first national park as a way to preserve and protect the land for the “benefit and enjoyment of future generations.” (National Park Service) Yellowstone National Park covers a vast area in the Northwestern United States. Its landscape is very complex and ever changing thanks to the many geological forces that are found there. In fact, the unique geological features such as the geysers, hot springs, steam vents, among many others, are what lead to Yellowstone being named a national park. The remainder of this paper will describe Yellowstone in more detail, and cover its size, location, altitude, climate, distinctive features, geologic history, and the positive and negative effects of human involvement. Size, Location, Altitude, Land Attributes, and Climate

Yellowstone National Park is larger than the states of Rhode Island and Delaware combined. It covers 3,472 square miles, contains more than 2.2 million acres, and spans three states, with 96% of the park being located in Wyoming, 3% in Montana, and 1% in Idaho. Yellowstone’s highest point, located at Eagle Peak, is 11,358 feet above sea level, and its lowest point, Reese Creek, is 5,282 feet. The park is composed of nearly 80% coniferous forest, 15% grassland, and 5% is covered by water. It is home to approximately 67 species of mammals, including grizzly and black bears, bison, and the endangered gray wolf. Temperatures range from an average of 9º Fahrenheit in January, to 80º Fahrenheit in July. Precipitation ranges from 10 inches in the northern to 80 inches in the southern regions of the park. (National Park Service) Geologic History, Formation, and Features

Yellowstone National Park is one of the most geologically dynamic locations on Earth. As such, its complete geological history is beyond the scope of this report, so only some of the major events that have helped to shape today’s Yellowstone will be discussed. Yellowstone sits atop a "hot spot" in the Earth’s mantle. A hot spot is defined by Merriam Webster as “a place in the upper mantle of the earth at which hot magma from the lower mantle upwells to melt through the crust usually in the interior of a tectonic plate to form a volcanic feature.” (Merriam-Webster) This process brings heat from the Earth’s interior close to the surface. There are approximately 40-50 of these hot spots on Earth, and Yellowstone is among the most active. The hot spot at Yellowstone meets the base of the North American tectonic plate, and the two have interacted for as long as 17 million years. This interaction has caused catastrophic volcanic eruptions and frequent earthquakes. (Dzurisin) Ancient volcanic eruptions that have occurred at Yellowstone are among the largest and most powerful that have ever occurred on earth. Three major eruptions have shaped today’s Yellowstone. During each of these eruptions, huge volumes of rhyolitic magma, mixed with red-hot pumice, volcanic ash, and gas, flowed in all directions. The rapid expelling of such enormous amounts of magma caused the ground to collapse, thus forming today’s calderas. The first eruption happened about 2.1 million years ago. The volume of material that was ejected during this eruption is estimated to have been about 600 cubic miles, which is about 6,000 times the amount that was ejected during the 1980 eruption of Mt. St. Helens in Washington. As the ground around the magma chamber sunk, the first of Yellowstone’s three calderas was formed south of Mammoth Hot Springs. Ash from this eruption has been found as far away as Missouri. The second Yellowstone eruption happened about 1.3 million years ago near the western edge of the first caldera, creating a...
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