Witte Hi Pt S P Geology

It was probably during this time that a stream

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Unformatted text preview: anced over northern New Jersey at least three times (fig. 10). From oldest to youngest, these glaciations are named the pre-Illinoian, Illinoian, and late Wisconsinan. Glaciers are large bodies of ice that form over long periods from the gradual buildup of compacted and recrystallized snow. Eventually, the ice becomes thick enough to High Point State Park flow under the stress of its Passaic own weight. Ice sheets are Sussex thick glaciers that cover large Warren Bergen Morris parts of continents. In North lW Belvidere America the Laurentide and Cordilleran ice sheets grew Essex to enormous sizes. It is I Hudson estimated that their centers Union Perth were as much as 10,000 Amboy pI Staten feet thick. At High Point, Island Hunterdon Somerset the ice may have been 2000 Middlesex feet thick when the North American ice sheets were at Mercer Monmouth their maximum size. area of detail The North American ice sheets were centered Figure 10. Limits of glaciations in New in the subarctic regions of Jersey. The trace of the lw limit generally Canada and grew and spread marks the Terminal Moraine. Key: lW - late outward during periods when Wisconsinan, I - Illinoian, and pI - prethe northern hemisphere was Illinoian. 13 colder than it is now. Current ideas are that small changes in the earth’s orbit, tilt of its axis, direction of ocean currents and storms, and volcanic dust in the atmosphere may have all contributed to global cooling. The geologic record shows that the growth and decay of continental ice sheets in the northern hemisphere was cyclic. In New Jersey, the climate varied from arctic or boreal during glacial periods to temperate or subtropical during interglacial periods. Today we are considered to be in an interglacial stage. A precise age of the oldest glacial deposits is uncertain. Their extensive weathering and poor preservation suggest they were laid down more than 800,000 years ago. Later, during the Illinoian stage about 150,000 years ago, an ice sheet again covered northe...
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This document was uploaded on 03/21/2014 for the course GEOL 3265 at Kean.

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