The granite in the Sierra Nevada Range and the glacier-carved landscape of Yosemite National Park allows the geologic history of the area to be broken into two distinct parts. First, the deposition and deformation of metamorphic rocks and emplacement of granitic rocks during the Paleozoic and Mesozoic, and secondly, the uplift, erosion, and glaciation during the Cenozoic that produced the modern landscape (United States of America). Significant chapters in this geologic history include the assembly of California, the intrusion of the Sierra Nevada Batholith, building of the Sierra Nevada, and erosion by glaciers (United States of America). The glaciation has led to iconic landmarks that are known around the world, such as Yosemite Falls, Yosemite Valley, and Half Dome (United States).
It is well known that glaciation is the cause for how Yosemite looks today, but it is not as well known what happened before the relatively recent glaciation which happened about 15,000 years ago. The geologic history of Yosemite and the surrounding area starts 500 million years ago in the Paleozoic Era when the area was still under the waters of the Pacific Ocean (Beatty). This area had a passive fault, similar to the east coast of the United States today. The mud and silt from the ocean settled in the Yosemite area and eventually became shale, siltstone, and carbonate rocks (United States of America). By the end of the Ordovician Period, the fault changed from a passive to an active fault. The oceanic plate started to subduct under the continental crust and push the shale upward, forming the first mountains in the western United States. At first, these were volcanic islands off the coast. This formation is called the Shoo Fly Complex. T...
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...se two tectonic plates generated intense friction and pressure that generated enough heat to melt rocks. The descent of denser oceanic Farallon Plate into the asthenosphere produced magma that was made from basalt or andesite. Which is dark colored rocks with little silica. The buoyant magma pushed through the silica-rich continental crust, partially melting the crust that it moved though, and becoming more granitic in composition. About 100 million years ago, the granitic magma pooled at depths of only 2 to 5 miles beneath the surface (United States of America). The granitic terrain that makes up the Sierra, was once thought to have only local variations but was produced from one large mass of rock. It has been discovered however that hundreds of intrusions caused the variations in the granite that is displayed in Yosemite and in the Sierra Nevada range (Huber).
...e morphed it into the quartzite that is seen surrounding the butte (4). Rocks that undergo this process are called metamorphic rock, which is the same as the rock seen years ago by dinosaurs and other extinct creatures. The quartzite rocks were formerly seafloor sediment that was forced upwards, and then surrounded by lava basalt flows. Once erupted through fissures and floods through out most of the area, lava flow eventually created enough basalt to form a thickness of about 1.8 kilometers (1). All of this basalt flow eventually led to the covering of most mountains, leaving the buttes uncovered. The igneous lava flows and loess is reasons that the Palouse consists of such sprawling hills, and rich soil for farming (2). In result of the lava flows, the Precambrian rock Quartzite was formed. And lastly covered by the glacial loess, which were carried by the wind.
Miesse, Willian C. "Mount Shasta Geology and History." USGS: Volcano Hazards Program - Mount Shasta Geology and History. College of the Siskiyous Library, n.d. Web. 01 May 2014.
Most of Arizona’s earthquakes are associated with the San Andreas fault as most of Arizona’s earthquakes are shocks from epicenters located in California. Arizona has had earthquakes with epicenters located in its borders and just like the ones located near the San Andreas fault, they are linked to a transform plate boundary and are dip-slip earthquakes. Much of the focus of these earthquakes can be centered around the Grand Canyon as much of the after-effects of these earthquakes caused phenomenons to occur in the Grand Canyon. Many rockslides took place in the Grand Canyon and plenty of the cracks found in the canyon’s rock layers are attributed to some of the earthquakes that took place in Arizona since the geologic landscape formed its current
The Franciscan Terrane of central California represents an accretionary complex formed by long-term subduction of an oceanic plate under the Western margin of the North American craton. The Franciscan complex is composed of three distinguishable belts: the eastern belt (Yolla Bolly and Pickett Peak terranes), the central belt, and the coastal belt. Age and metamorphic grade of the belts decreases to the west (Blake and Jones, 1981). Formation of the accretionary complex began during the late Jurassic in the eastern belt and has continued into the Miocene along the western coastal belt. The complex trends NNW and is bounded by the San Andreas Fault to the east and by the coastal range fault to the west. The coast range fault separates the Franciscan complex with the partly coeval Great Valley sequence. Debate exists over the tectonic evolution of the Franciscan, centered around the geographic origin of the Franciscan rock units.
The geology, its history, and the presence of past civilizations contribute to much of the significance of Mesa Verde National Park. The interconnectedness of these aspects should also be noted. If not for the weathering processes and changes in sea level this formation would not exist. Without it, the ancient people would not have been able to reside within Mesa Verde. This National Park now serves as a tool to help conserve the remains of these past civilizations as well as to help educate today’s society on the significance behind this astonishing geologic
Shown in the picture above is volcanic extrusive igneous rock known as andesite. They were imported here to Laguna Beach to help minimize erosion (Merton Hill, p. 10-11). Extrusive Igneous rocks are formed on Earths surface due to lava quickly cooling or mixing with different materials such as ash or cinders from an eruption. There are two different types of extrusive igneous rocks; Plutonic and Volcanic. Andesite is known for being gray in color and being made up of very coarse grainy textures, which make it much harder to break down than sedimentary rocks. Unlike loose gravel and other sediments igneous rocks are known for being able to slow down seismic waves from earthquakes which cause less damage to surface structures.
There exists the Dome of Yosemite by Albert Bierstadt, with dramatic rock outcroppings, the sun burst...
Glaciers are an integral part of the world’s climate. In fact, as Richard Armstrong of the University of Colorado says, “Glaciers are key indicators in monitoring and detecting climate change” (Univ. of Colorado, Boulder, 2003, p. 1). Not only are they an important part of monitoring current climate, they can hold many keys to the past. Glaciers are in fact, “a source of paleoclimate data…” (Meier and Dyurgerov, 1980, p. 37). This paleoclimate data can give geologists information on the conditions that were present at the time of the glaciers birth, as well as the approximate age. This has an important role in the geologic time scale of the Colorado Rocky Mountains. These Glaciers played a role in the carving of the present day Rocky Mountains in Colorado, which will be the primary focus of this paper. In addition, glacial formations will be discussed to give the reader background information and the future of the Glaciers in Colorado will close this paper.
Stone Mountain is an igneous intrusion often referred to as a geological pluton. The granite pluton is part of the Piedmont Plateau region of the Appalachian Mountains and was formed along the same geological fault line that created the Blue Ridge Mountains but is not part of the Blue Ridge chain. Northern and Eastern Georgia have relatively frequent seismic activity with ten quakes recorded in 2013. These quakes occurred at an average depth of 9.6 km which make them less obvious and cause less property damage. This same seismic activity created Stone Mountain 300 million years ago during the last stages of the Alleghenian Orogeny when massive tectonic plate shifting allowed a large mass of magma from beneath the earth’s crust to well up . Flow structure markings on the mountain show the stone was formed underground after several eruption pulses failed to break through and then cooled to form, ultimately creating granite mass that rises 825 feet above ground, extends 9 miles underground and has a circumference of 5 miles at its base, making it the largest exposed dome in the world . Rising 1683 feet above sea level the summit of the dome is bare stone with rock pools and an unobstructed view that extends to Kennesaw Mountain, Amicacola Falls and Mt. Yonah state parks, including a breathtaking view of the Atlanta Skyline.
...the only major geologic event in the history of the Appalachians. Several glaciers have covered parts of the Northern Appalachians over the last three million years. (Appalachian tales) The mountains have been there ever since and that is how they were formed.
In the 1800’s into the early 1900’s a man named John Muir began to explore the western American lands. He traveled down South and up North. But, when he reached Yosemite Valley, his life changed. As said in John Muir’s Wild America, written by Tom Melham, “Following the forest-lined mountain trails, Muir climbed higher into the Sierra Nevada: suddenly, a deep valley enclosed by colossal steeps and mighty water falls yawned before him. Spell bound, he entered Yosemite Valley” (79). Muir’s travels and adventures, highlighted in Melham’s book, explain this man’s love of the wilderness. Yosemite Valley was like a wide, open home to Muir, who, lived alone and discovered new landings and important later landmarks that create the aura of Yosemite National Park. Yosemite Valley was given to the state of California in 1864, part of the continuous idea of Manifest Destiny, later, in 1890; Yosemite became one of the first National Parks (“World Book”). Uniquely, the longer Muir stayed the more that he...
Basalt forms due to the partial melting of the layer of the mantle called the asthenosphere. The asthenosphere is the plastic zone of the mantle beneath the rigid lithosphere. Mantle plumes coming from the mesosphere can cause the asthenosphere to melt with heat or even if pressure decreases, which is called decompression melting (Richard 2011). The magma that forms from this melting is mafic magma that solidifies once it reaches the earth’s surface and cools quickly. The above process mainly occurs mainly during intraplate igneous activity which is the main explanation for volcanic activity that occurs a long distance away from a plate boundary. If the tectonic plate above the mantle plume is moving it can create a string of volcanic activity such as in Hawaii. See Fig 2.
The Little Missouri River eroding the mountain range is the reason that the park is as it looks today. The park is believed to be <60 million years old. Over 60 million years ago volcanos all over the west were erupting and spitting out amounts of ash. The rivers near the volcanos were gathering. The rivers began to dry out, leveeing the ash behind. The ash was being dried in layers and turned into sandstone, siltstone and mudstone while the ash layers became bentonite clay. This Bentonite clay is dangerous because it gets people stuck, like quick sand it is located throughout the park. It can pull the car tires un...
Yosemite and its history, young to old the story of an area of land that is doomed to be mined, forcibly stripped naked of its natural resources. In 1864 Yosemite land grant was signed into act by president Abraham Lincoln, the first area of land set aside for preservation and protection. Yosemite being a very important historical plot of land, some time ago president Theodore Roosevelt visited the park managing to disappear from the secret service with John Muir. Through the years the contrast of ideas between the industrialists and the preservationists have clashed, Yosemite’s history both interesting and mysterious but more importantly inevitable .
The Cascade Range, which extends northward from California into British Columbia in Canada, rests on the North American Plate. The North American plate moves in a southward direction. The adjacent Pacific Plate, which is an oceanic plate, moves northward along the North American Plate, resulting in a subduction zone, in which the Pacific Plate is pushed upwards into the North American Plate, pushing up the Cascade Range. (Abbott, P.L., 2014) The frequent volcanic eruptions in the Cascade Range evidence the continued active subduction activity in this area. Subduction, in this case, pushes the older oceanic crust back into the mantle. In the Cascades range, this occurs as subduction of three smaller tectonic plates: the Juan de Fuca, Explorer and Gorda Plates. These are believed to be remnants of a much larger plate that broke apart. These smaller plates continue to slide underneath North America at a rate of approximately 3.5 centimeters per year. As these oceanic plates slide under the continental plate of North America, they dip at a sharp angle, meaning as the plates go deeper into the continental plate, they get hotter.