Witte Hi Pt S P Geology

A precise age of the oldest glacial deposits is

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Unformatted text preview: rn New Jersey. Most recently, New Jersey was glaciated during the late Wisconsinan substage, about 20,000 years ago. Each ice sheet modified the landscape. Valleys underlain by weak rock were widened and deepened; bedrock ridges, hills, and slopes were slightly worn down and streamlined, and most surface materials were eroded. Rocks, gravel, sand, silt, and clay entrained in the ice sheets were deposited as till, an unsorted mixture of clay- to boulder-sized material. This material was laid down on the bedrock surface in sheets, in streamlined hills called drumlins, and in ridges laid down along the former edge of the ice sheet called moraines. Stratified sediment consisting of sorted and layered gravel, sand, and silt was deposited by glacial meltwater streams in valleys that drained away from the glacier and in glacial lakes. The harsh, cold climate immediately south of the ice sheets enhanced erosion of surficial sediment by mass wasting, and accelerated the physical weathering of bedrock, largely by frost shattering. In contrast, temperate and subtropical climates during interglacial periods lessened rates of physical weathering, but increased rates of chemical weathering, which led to the formation of thick decomposed bedrock. Local History High Point State Park lies entirely within the limit of the last glaciation and only glacial deposits (fig. 11) and erosional features associated with the late Wisconsinan ice sheet are preserved here. Older glacial deposits and features were buried beneath younger glacial sediment or were eroded during the last glaciation. The late Wisconsinan advance of ice into northwestern New Jersey consisted of ice lobes initially moving southwestward down Minisink and Kittatinny Valleys. In time, the ice became thick enough to flow over Kittatinny Mountain and, turning south, it flowed across the 14 HIGH POINT STATE PARK SURFICIAL GEOLOGY swamp-low area of waterlogged ground t t msk t Steeny t K PA R t RIDGE R s D t s t s t ma t s s s s s m...
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This document was uploaded on 03/21/2014 for the course GEOL 3265 at Kean.

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