Environmental Geology Essay Example | Topics and Well Written Essays - 1000 words

Environmental Geology - Essay Example As the tectonic activity continued during next several million years the initial rock had influenced a series of future changes as the empty cracks in the rock were again filled with liquid magma, which later formed crystal fractions inside the granite mass. The irregular and wavy structure of granite rock witnesses for tectonic and geological activity at the primary stage of rock formation, when the future granite formation was under a high temperature and was plastic for deformations. The motion of tectonic plates and elevation caused wavy structure. Besides it was prompted by changing climate and outside physical influence such as weathering and changing temperature regime. The second unit of the outcrop is represented by sandstone which is a sedimentary rock. The presence of sandstone witnesses for the absence of serious tectonic and geological changes in later geological epochs. The next geological periods in this outcrop starting from Triassic and up to Jurassic in Mesozoic era are characterized by the presence of sea life in that region. It means that the territories taken by magmatic and granite deposits were gradually flooded by sea waters. These were the conditions essential for the future forming of sandstone as the waters brought a lot of sedimentary rocks and sand to that territory. During million years these sedimentary rocks and sand were concentrating and under the high pressure they turned into solid rock such as sandstone which on the hand with sand particles contains a reasonable amount of cement which glued sand and turned it into concrete structure. The upper stratum gradually changes into marl. Marl stratum was formed by sedimentary particles which on the hand with sand particles included clay particles and calcium carbonate particles. During million years of depositing and under a pressure these particles transformed into a solid rock formed predominantly by clay and CaCO3 elements called marl. The presence of sand and clay witness that this stratum was formed during Mesozoic era. The last stratum represented by limestone also witnesses that the territory of outcrop was still occupied by water and that it was rich in the sea life. The limestone stratum was formed by sea organisms which could take dissolved calcium salts from the seawater. CaCO3 was a fundamental structure of their shells and skeletons and after millions years of high pressure and depositing it turned into limestone. Task 2 To the north from North-American platform there is situated a wide zone of Alpine suture represented by the Rocky Mountains and Cordeliers. This zone is characterized by tectonic and mobility of quasi-planar zones, which existed from prehistorically times as there existed such sutures as Hercinian, Caledonian and Cambrian. In Mesozoic era the Western part of North America also continued to experience tectonic movement conditions and besides there existed two zones of flexure where depositing of precipitation occurred: one of them occupied the stripe of the Rocky mountains from Alaska in the north to Colorado plateau in the south and another one stretched from Aleut islands through cascade mountains in Canada and Sierra-Nevada in the USA. Between these two flexure zones there was formed a zone which experienced little flexure.