Geology of Yellowstone Assignment

Geology of Yellowstone Assignment Words: 2678

Introduction 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.

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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 9?

Fahrenheit in January, to 80? 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. million years ago near the western edge of the first caldera, creating a new caldera known as the Henry’s Fork caldera in Idaho, just west of the park, and spewed enough material to cover 67 cubic miles. The third eruption happened about 640,000 years ago, and spewed 240 cubic miles of material. This third eruption created the third and largest of Yellowstone’s calderas, Yellowstone Caldera, which is 30 by 45 miles in size. The pyroclastic lava flows from this eruption formed the north wall of the caldera and are visible from the south-facing cliffs east of Madison. Solcomhouse) This third eruption is said to have vaporized an entire mountain range. Smaller eruptions have also helped to shape Today’s Yellowstone, such as one that occurred 174,000 years ago and created what is now the “West Thumb” of Yellowstone Lake. (National Park Service) Many sources say that a catastrophic eruption, such as those that have formed the three calderas at Yellowstone, is unlikely during the next several hundred years, but if one such eruption did occur it would devastate much of the United States and would have the potential to alter the global climate.

Lava flows of rhyolite and basalt have flowed through parts of Yellowstone as recently as 70,000 years ago. These lava flows destroyed everything in their paths while moving slowly at a rate of a few hundred feet per day, flowing months, or sometimes even several years. They are thick and cover as much as 130 square miles. They have nearly filled the Yellowstone Caldera, and spilled beyond the caldera’s border. These lava flows are responsible for forming four of the nine named plateaus in Yellowstone, including the Madison Plateau.

Visitors of the park drive and hike across these hardened lava flows even today. It is believed that future lava flows are more likely to occur than a catastrophic volcanic eruption, although there is no scientific evidence to indicate such a lava flow will occur soon. (Solcomhouse) Yellowstone’s volcano has created over 10,000 hydrothermal features including geysers, fumaroles, mudpots, and hot springs. More than 300 active geysers are found there, which is roughly half of those found on earth. A geyser is a type of hot spring that erupts periodically, and that ejects hot water and steam into the air.

Water from the surface seeps into the ground and comes into contact with rocks heated by magma. The hot water then rises through cracks and fissures in the earth. When this super heated water comes into contact with the cooler water above the weight and pressure causes an overflow, which relieves the pressure on the super-heated water, causing it to flash into steam. It is that flash that shoots the water and steam into the air. Fumaroles, also known as steam vents, are the hottest hydrothermal features at Yellowstone.

There is so little water in a fumarole, that what is there, turns to steam before it reaches the surface, unlike a geyser, which ejects steam and water. When the steam escapes, it often makes a hissing noise. Mudpots are thermal areas where sedimentary rocks are melted to clay from the hot water and the rising steam below. This rising steam forces its way to the surface causing the mud to burst upward. Hot springs are similar to geysers, but the channels beneath them are large enough to allow the water to circulate rapidly.

The rising hot water releases energy by evaporation or runoff, while convection currents return cooler water to the underground system. (YellowstoneNationalPark. Com) The scalding-hot waters from the spring provide habitat for thermophilic (heat-loving) microbial life, simple organisms believed to be similar to the first forms of life on Earth. These organisms often make the pools very colorful. Near these hot springs, another popular feature forms, travertine terraces. Heated water carrying dissolved calcium and bicarbonate, moves along the Morris-Mammoth Fault.

Step-like terraces are created when this heated water rises to the surface of the limestone and releases carbon dioxide, resulting in the deposit of calcium carbonate. This deposition occurs rapidly, thus the appearance of the terraces changes quickly. (National Park Service) The terraces often appear white and chalky, when fresh, but as they age and weather they often turn gray. Yellowstone is among the most seismically active areas in the United States. There are approximately 2,000 earthquakes each year there, although most are small enough that they are not felt.

In Yellowstone, this earthquake activity helps to maintain the hydrothermal activity that occurs there by “keeping the ‘plumbing’ system open. ” Without such small earthquakes, the cracks in the earth that supply hot water to the geysers and hot springs would eventually seal from the deposit of minerals. (National Park Service) While much of the landscape at Yellowstone has been affected by the volcanic activity which occurs there, not all of it has. Precambrian igneous and metamorphic rocks, including gneisses and schists, in the northeastern section of the park date back at least 2. billion years. These rocks are hard and erode slowly. Sandstones and shales, which were deposited when seas covered the lands of Yellowstone were deposited in the Paleozoic and Mesozoic eras (between 70-140 million years ago) and can be seen in the Gallatin mountain range and at Mount Everts. These sedimentary rocks tend to be particularly sensitive to weathering and erosion, which are common in Yellowstone due to the freezing and thawing action of the landscape. Massive erosion has led to the discovery of many petrified trees in the northern and eastern regions of the park. National Park Service) The Grand Canyon of the Yellowstone River was also formed as a result of erosion. The canyon is the primary geologic feature in the Canyon District of the park and is roughly twenty miles long. Its depth is from 800 to 1200 feet while its width is from 1,500 to 4,000 feet. The canyon itself is no more than 14,000 years old, but there is little information available about the sequence of events that led to its formation. Little is known about the canyon, and studies that have been conducted are believed to be inaccurate. National Park Service). The forming of the Absaroka Mountain Range, a sub-range of the Rocky Mountains, and which forms the eastern boundary of Yellowstone National Park was not related to the Yellowstone volcano. The Absarokas formed as a result of andesitic volcanic activity from a chain of volcanoes that erupted approximately 50 million years ago when a subducting ocean plate dived beneath the North America’s western edge. (USGS) Glaciation has also played a part in the forming of the landscape at Yellowstone National Park.

There have been three known periods of glaciation at the park, although succeeding periods of glaciation are believed to have destroyed most of the evidence from prior periods. The most recent major glaciation at Yellowstone is known as the Pinedale. Although the Pinedale period is the most studied at Yellowstone, the history of the glacier remains hard to prove. Scientists believe with confidence that it ended between 13,000-14,000 years ago. At Pinedale’s peak, an ice cap about 4,000 feet thick covered Yellowstone.

This ice cap formed here, in part due to the magmatic activity beneath the park that had pushed the landscape to a higher elevation than the surrounding area. Glaciers advanced and retreated from Beartooth Plateau, and glacial dams backed up depositing sediment. Catastrophic floods occurred when the dams at Lamar Valley lifted, which formed the landscape near the north entrance of the park. Today, there are no glaciers in Yellowstone National Park. (National Park Service) Effects of Human Involvement on Yellowstone National Park

Humans have had both positive and negative effects on Yellowstone National Park. Some of the negative effects have been vandalism, failure of park visitors to remain on marked paths and roads, and failure to extinguish fires. Coins, rocks, garbage, and other debris have often been found in the narrow vents of geysers and hot springs. This has sometimes caused a geothermal feature to become plugged which can disrupt its natural activity; often little can be done to restore a feature once such damage has occurred.

Damage has also occurred when people climb on certain rocks or formations, breaking off pieces either by accident or for souvenirs. (National Park Service) Wildfires are natural in the Yellowstone area. Several fires caused by lightning are reported each year, and since 1988 the number of natural fires has continually increased. However, in the summer of 1988, thirty-six percent of the acreage of the park was burned due, in part, to fires set by humans, and in part to the failure of park officials to have an adequate fire management plan.

Firefighting efforts during that year alone cost more than $120 million, and would have been more if not for early snowfall in the park in September. Some of the most positive effects of humans on the park include conservation efforts. While humans can negatively affect the geothermal activity of geysers, and other thermal features, as indicated above, the conservation efforts of park officials and government have also helped to preserve the geothermal activity that occurs in Yellowstone. Nearly 75% of the World’s geothermal features are found in Yellowstone.

In other areas around the world, geothermal development has drastically reduced the amount of active geysers. So far geothermal development has been prohibited in Yellowstone and the surrounding areas. (National Park Service) Animal conservation has also played a big part in Yellowstone. American buffalo once roamed North America freely. Their numbers were estimated from 30-75 million. By the late 1800’s they had almost been eradicated. In 1894 Congress passed a law making it illegal to hunt buffalo in Yellowstone National Park.

Today it is estimated that only 200,000 buffalo remain in the United States. Of that number it is estimated, as of 1998, that 4,000 of those live in Yellowstone National Park, while the majority of others live in privately owned herds. (U. S. Fish & Wildlife Service) Another success story is that of the Gray wolf. The Gray wolf was placed on the Endangered Species List in 1973. At that time it was estimated that only a few hundred remained in the United States and Mexico. Gray wolves were reintroduced into Yellowstone National Park in 1995 and 1996.

By late 2006, it was estimated that there were about 1,100 wolves in the greater Yellowstone area alone. The recovery has been so successful, that it has been proposed that the Gray wolf be removed from the threatened and endangered species list in the Rocky Mountain area. (U. S. Fish & Wildlife Service). Conclusion Yellowstone National Park has a rich geological history thanks in part to volcanism, its “hot spot,” and its history of glaciations. It is home to the majority of the geysers and other geothermal features found around the World, and it is home to some of North America’s most revered animals.

Without the conservation efforts that have taken place there, some of these geothermal features and animals may have been lost forever. The continued study of Yellowstone’s geology is important due to the potential of its volcano to affect a large portion of the United States and possibly even the World. It is easy to see why Yellowstone was named the World’s first National Park. It is among the most spectacular places in the United States and perhaps the World. References Dzurisin, Christiansen, and Pierce. 1995. Yellowstone: Restless Volcanic Giant: VOLCANO HAZARDS FACT SHEET. Merriam-Webster.

October 31, 2011. National Park Service. U. S. Department of the Interior. November 1, 2011. Canyon Area Natural Highlights. < http://www. nps. gov/yell/planyourvisit/ncanyon. htm> National Park Service. U. S. Department of the Interior. October 27, 2011. Geothermal Resources. National Park Service. U. S. Department of the Interior. October 26, 2011. History and Culture. National Park Service. U. S. Department of the Interior. October 26, 2011. Yellowstone Fact Sheet. National Park Service. U. S. Department of the Interior. October 26, 2011. National Park Service. U. S. Department of the Interior.

October 26, 2011. Yellowstone Resources and Issues. National Park Service. U. S. Department of the Interior. November 3, 2011. Solcomhouse. November 1, 2011. Yellowstone Supervolcano. U. S. Fish & Wildlife Service. October 27. 2011. American buffalo. U. S. Fish & Wildlife Service. October 27, 2011. Gray Wolf. < http://www. fws. gov/home/feature/2007/gray_wolf_factsheet. pdf> USGS. October 31, 2011. America’s Volcanic Past. ; http://vulcan. wr. usgs. gov/LivingWith/VolcanicPast/Places/volcanic_past_montana. html; YellowstoneNationalPark. Com. November 3, 2011. Geology.

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