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Monday, February 12, 2007

lets further explore the features of Jurassic period with me IRVIN.

Jurassic Geography
The Jurassic saw disintegration of Pangea that began in the Triassic continuing apace. The supercontinent begins to rotate, but the different components of the huge mass rotated at different rates and then in different directions, forming rift valleys. One of these opened the southern part of the North Atlantic Ocean and continued westward into the Gulf of Mexico. This was North America drifting westward, opening the Gulf of Mexico, forming the central Atlantic. As Greenland-North America separate from Europe-Africa and slide over the Pacific Ocean floor, mountain-building events are triggered that created the North American Cordillera (the Rocky Mountains and the Sierra Nevada). A huge arc was built on western North America and the Nevadan orogeny begins. Cimmeria begins its collision with Laurasia to form the Cimmerian orogeny.
In Gondwana the initial narrow split between South America and Africa that began during the Triassic widened into a configuration resembling the present-day Red Sea. New sea floor formed along the nascent South Atlantic. This lengthened into a long, narrow seaway between South America and Africa. The Western side South America was subducted by an opposing oceanic plate. A great rift separates Antarctica from the southern ends of South America and Africa, developing an arm that extends eastward from South Africa along what is presently the eastern side of India, which began drifting northward.. Volcanoes located along these rifts erupted and issued huge amounts of basaltic lavas. The separated segments of Gondwanaland move slowly northward, turning gently counter-clockwise. Early rifting along the Australia-Antarctica join provided moist forested conditions that became coal deposits.
During the Jurassic the extent of the oceans was far more widespread then they had been in the Triassic. The Jurassic sea level rose and flooded large portions of the continents. Shallow epi-continental seas spilled out of the Tethys and Proto-Atlantic and spread across Europe, leaving a rich sedimentary record of limestone with fine clastics adjacent to the highlands. These warm shallow seas were home to a rich diversity of life. The spreading ocean crawled across Russia and into what is now the Arctic Sea before retreating at the end of the period. Meanwhile much of central North America was flooded by wide sea way that at its height extended into central Utah. This continent-wide embayment has been dubbed the Sundance Sea, and was fringed by strips of continental land on three sides.

there is lot more to come under jurassic period just wait and watch ! please feel free to use the links in the matter for more information.

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