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Witte Hi Pt S P Geology

Subangular to subrounded stones of quartz pebble

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Unformatted text preview: ified mix of clay- to boulder-sized material. 1 2 3 4 5 basal till flowtill planar beds of gravel and sand inclined beds of sand and some gravel laminated beds of silt, clay, and very fine sand 0 1 mile vertical exaggeration x20 moraine 1 delta delta GL 2 3 3 debris bands 4 4 lacustrine fan 3 vel lake le bed rock IER AC meltwater stream 4 ottom lake b 1 5 1 Figure 13. Block diagram showing the depositional setting of glacial sediments with photo insets of till and outwash. 18 at the glacier’s base (fig. 13). Overlying this lower compact till is a thin, discontinuous, loose, poorly sorted silty sand and sand containing as much as 35 percent pebbles, cobbles, boulders, and lenses of sorted sand, gravel, and silt. Overall, stones are typically more angular than those in the underlying till. This material is debris that was released from the glacier by melting at the glacier’s terminus. It may have been let down slowly by melting ice or flowed off the ice onto adjacent land. This material is called ablation till and flow till respectively (fig. 13). Frost heaving, burrowing animals and insects, and root growth have also altered the upper few feet of till making it less compact, and reorienting its stones. A glacial erratic is a rock, commonly a boulder, that was picked up and carried by the glacier and deposited some distance from its source, often many miles. Most erratics show evidence of glacial erosion by their subrounded shape, flattened sides, and striated or polished surfaces. They are found throughout the park and were largely plucked from nearby outcrops on Kittatinny Mountain and in Kittatinny Valley. A few are larger than 10 feet in diameter. The most remarkable are the Martinsburg sandstone boulders that were carried up and out of Kittatinny Valley to the top of Kittatinny Mountain. There they rest, as much as 900 feet above the valley floor. Glacial Landforms Landforms in the park that were created by the glacier include drumlins, end moraines, and kettles. Drumlins are oval-shaped hills consisting of till that were deposited at the g...
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