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Hi, need to submit a 750 words essay on the topic The Historical Formation of West Virginia.Download file "The Historical Formation of West Virginia" to see previous pages... According to Lessing (199
Hi, need to submit a 750 words essay on the topic The Historical Formation of West Virginia.Download file "The Historical Formation of West Virginia" to see previous pages...
According to Lessing (1996) "West Virginia basically consists of two areas: namely, the western area which is called the Appalachian Plateau Province, a plateau of relatively flat-lying rocks and the eastern part in which the Valley and Ridge Province lay which consist of folded and faulted rocks. These two areas are divided by the Allegheny Front.
In the eastern part of West Virginia the oldest rocks can be found and as one proceeds westward, the rocks are younger and younger".
At the beginning of the Devonian Period the Helderberg group was being formed, followed by the Oriskany Formation, the Millboro Formation, the Brallier Formation, the Foreknobs Formation and the Hampshire Formation. In this report the most important geological features are being explained in a historical order.
At the beginning of the Devonian time (Upper Devonian) the Helderberg Group was being formed. Baedke and Fichter (2000) state that "during the end of the previous period (which is called the Silurian Period) West Virginia had been a desert since the sea had regressed. But by the beginning of the Devonian Time the Tippecanoe sea began its major transgression, which caused a rise in sea level and as a result of this the land flooded". According to Dorobek and Read (1986) the Helderberg Group is a "is a mix of siliciclastic-carbonate sediments that was formed during a relativ stable tectonic environment, namely on a slope that consisted of low-relief tectonic highlands on the eastern side of the Appalachian Plateau Province. Dorobek at al. state that the Helderberg Group lasted bout 8-10 million years. In this timeperiod three transgressive-regressive eras can be distinguished from each other. Each sequence was shaped over 2-3 million years. Finally the Helderberg Group was buried by thick Middle Devonian siliciclastic sediments".
"By the end of the Upper Devonian Period the sea level had reduced again because of a major regression of the Tippecanoe sea. Rocks that had been deposited in West Virginia were removed because of erosion. Pure black quartz sand was spread across West Virginia through which the Oriskany formation was formed. This all happened during a rare period of tectonic stability" (Baedke and Fichter (2000)).
"Brame 2001 claims that at the beginning of the Middle Devonian Period the sea level changed again because of transgression of the sea. Through the rise of the sealevel the Millboro sequence, a deep water black shale, could be formed" (pp25-26).
During the end of the Middle Devonian Period (when the tectonics where unstable again) and the beginning of the Lower Devonian Period the Brallier sequence was formed. According to Brame (2001) "a part of the Brallier Formation, namely the Back Creek Silt-stone Member, has been formed by a tectonically caused clastic wedge. Brame (2001) states that another sequence of the Brallier Formation, namely the Minnehaha Springs Member, has been formed by erosion as a result of sea-level regressions" (pp27-29).
During the Lower Devonian Period, when the shoreline was shifting, the Foreknobs Formation was deposited in a shelf environment. "The Foreknobs exist according to Brame (2001) of siltstone and sandstone. Brame (2001) adds that "the Foreknobs Formation was separated into five sequences: namely, the Mallow, Briery Gap, Blizzard, Pound Sandstone, and Red Lick.