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Unformatted text preview: led alluvium, consist of sand and gravel laid
down in channels, and finer sediment laid down on narrow flood
plains. Many modern streams in High Point flow along channels
originally cut by glacial meltwater. In a few places, such as the
ravine northwest of Steeny Kill Lake (Plate 1), these channels are
as much as 60 feet deep. Alluvial fans formed where tributaries
entered larger valleys and deposited their heavier loads. Their
composition is highly variable, chiefly derived from local surficial
materials laid down by intermittent and perennial streams.
Most are entrenched by modern streams. This suggests they are
probably of late Wisconsinan and early Holocene age and formed
when rigorous climate, sparse vegetation, and abundant sediment
favored their formation.
Swamps and bogs contain sediment and organic material that
can be used to reconstruct past climates. Because their materials
were laid down layer upon layer, they may preserve a record from
the end of the Ice Age to the present. Pollen and other plant material
retrieved from swamps may be identified and provide dates used
to interpret past climate. Several studies of bogs and swamps in
northwestern New Jersey and northeastern Pennsylvania have
established a dated pollen stratigraphy that nearly goes back to
the onset of deglaciation. The pollen records the transition from
tundra with sparse vegetation, to an open parkland of sedge and
grass with scattered stands of spruce and fir. From about 14,000
22 to 11,000 years ago a dense closed boreal forest developed that
consisted largely of spruce and fir blanketing the uplands. This
was followed by a period (11, 000 to 9,700 years ago) when pine
became dominant. About 9,400 years ago oak became dominant
and displaced the conifers, signaling the change from a boreal to
a temperate climate.
Mastodon remains, excavated from Shotwell Pond in Stokes
State Forest show the presence of these large mammals on Kittatinny
Mountain during the close of the Ice Age. They disappeared from
this area about 12,000 years ago, presum...
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