Geologic Provinces of the United States: Appalachian
Highlands
Entrance to Delaware Water Gap.
Photo by Jack B Epstein, USGS.
The entrance to Delaware Water Gap National Recreation
Area as viewed from atop Kittatinny Mountain, Pennsylvania on
the right, New Jersey on the left. The Delaware River flows through
the constricted gap behind us, and as it widens into the valley
beyond and as its velocity lessens, it drops a streamlined bar,
Arrow Island. Between the mountain, held up by Quartzites of
the Silurian Shawangunk Formation, and the Precambrian
metamorphic rocks of the New Jersey Highlands in the distance,
is Wallkill Valley, underlain by Cambrian and Ordovician limestone
and slate. The Recreation Area, in proximity to the New York-Philadlephia
metropolitan complex, is the most heavily visited National Park
facility in the eastern United States, attracting more than four
million visitors a year.
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