Thursday, October 31, 2019
Geology Essay Example | Topics and Well Written Essays - 250 words
Geology - Essay Example aconic Orogeny or the building activity of a chain of mountains which is presently recognized as the Manhattan Formation mainly consisting of a metamorphic rock called schist derived from the former event of layered sedimentation. Umpire Rock is composed principally of Manhattan schist, making 90 percent of the Manhattan bedrock. The schist is found to be a mica-flecked stone hat with high durability, closely underlying the entire Central Park, dabbled with rock outcrops. Being a huge part of the Manhattan Formation made of schist, Umpire Rock is mostly a metamorphosed, highly deformed rock with great amount of folding. Physically, it appears as a sparkling rock once hit by sunlight, characteristic of mica flakes comprising much of the rock unit. The surface of the rockÃ¢â¬â¢s slope possesses five glacial grooves and these massive grooves had been carved by glaciers during the last ice age when glacial erosion brought about classic landforms. A fairly straight layer of granite approximately 2 to 3 inches wide is designated three feet from the base of the slope, bearing a band of pegmatite underneath. The pegmatite curves up along the slope following the schistÃ¢â¬â¢s pattern of folded layers and occurs to cut across the granite at the spot where two layers converge. The cliffÃ¢â¬â¢s intricate sculptural folds are such an admirable sight. Central Park Rocks are wholly evident of ancient bedrock upon which epochal events had transpired. Across the grain, light-colored veins of granite and coarser granite pegmatite may be detected visibly. Schimmrich, Steven. Ã¢â¬Å"Umpire (Rat) Rock in Central Park.Ã¢â¬ Hudson Valley Geologist. 27 Mar 2011. Web. 21 Jan 2012.