Witte Hi Pt S P Geology

A few are larger than 10 feet in diameter the most

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Unformatted text preview: lacier’s base. Most drumlins are in the western part of the park in places where till is thick. Their long direction is parallel to the direction of former glacier flow and they formed where the glacier streamlined loose surficial material or molded till at its base. Drumlins in the park trend due south to south 13o west, a more southerly direction than shown by nearby striations. This suggests that the drumlins formed when ice was much thicker, and its flow not as controlled by topography as it was when the striations were made. End moraines are bouldery, cross-valley ridges that mark the former lobate edge of the ice sheet. They consist of till with lenses of silt, sand, and gravel and exhibit ridge-and-kettle, and knob-and-kettle topography. In the park the moraines are named the Augusta, Montague, and Steeny Kill Lake (fig. 11). Kettles are depressions in the land that formed by the melting of stagnant ice blocks that were partly or completely buried in glacial material and then left 19 behind by the retreating ice sheet. Pine Swamp and the many depressions on the Augusta moraine are good examples. POSTGLACIAL HISTORY Ice retreated from New Jersey about 17,000 years ago. During the few thousand years following deglaciation, the harsh climate and sparse vegetation enhanced erosion of the land. Unconsolidated, water-saturated surficial materials were easily moved downhill by the constant pull of gravity. Disintegration of rock outcrops by frost shattering formed extensive accumulations of rock debris, called talus, at the base of cliffs on Kittatinny Mountain. Boulder fields formed at the base of slopes where rocks, transported by soil creep, came to rest. Other fields were formed where meltwater carried away the finer-grained material from till leaving behind the heavier stones. A few others may have been deposited directly by the glacier. In places boulders stand upright and some form crude stone circles. These may have been formed by frost heave, and possibly tree growth. Stream deposits, cal...
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