October 24, 2014
National Park Essay
Yosemite National Park first became a national park in 1890 with the help of Yosemite’s most famous advocate, John Muir. (APN Media, LLC, 2013) The park boasts some of the most easily recognizable geologic features in the world. Many of the most recognizable features are glacier cut granite walls and domes, and the waterfalls that fall off of them. The views of and from features like El Capitan, Half Dome, Glacier Point, Clouds Rest compared to the valley floors and meadows like Yosemite Valley, and Tuolumne Meadows are what make Yosemite a special place. For this paper we will discuss just two of the geological features listed above; Half Dome and Yosemite Valley. We will also discuss some of the geological concerns that Yosemite faces and why I choose to write about Yosemite. Half Dome is a large granite dome located on the east end of Yosemite Valley. (Scenic Wonders, 2014) The peak of Half Dome is over 4,700 feet above the valley floor. The Granite rock that makes up Half Dome was formed over 93 million years ago during the Cretaceous period. The granite was formed from magma that solidified underground. Through erosion of the sediment on top of the rock, the granite of Half Dome was exposed. Erosion is defined as “the process in which wind, water, or glaciers remove weathered particles from the environment.” (Renton, 2011) Half Dome got its shape from the geological process called sheeting. Sheeting is when an exposed rock fractures along is joints and breaks off. The granite of Half Dome is susceptible to this type of weathering and in 2009 a large section of granite actually fell off of the dome. Like most of Yosemite’s geological feature Half Dome is a product of glaciations. (Huber, 2014) Glaciation is “the process by which ice covers large amounts of the earth’s landmass.” (Renton, 2011) Yosemite Valley formed from the processes of glaciations and erosion. (Nation Park Service U.S....
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