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Unformatted text preview: ng opened the Atlantic Ocean more than 200
million years ago, in late Triassic time, newly formed streams along
the coast worked their way inland and captured parts of the inland
drainage. As time passed, streams flowing over weaker rock cut
valleys faster and deeper than those flowing over tough, harder rock.
Because belts of rock trend northeastward in northwestern New
Jersey, drainage developed along northeast- to southwest-trending
belts of weaker rock. In some places, hard, resistant rocks were
weakened by faults or numerous joints.
Streams cut through
these resistant ridges at their weakened points and formed features
like Delaware Water Gap and Culvers Gap.
Other geologists think that the ancestral Appalachian
Mountains were worn low and subsequently covered by a thick
layer of coastal plain sediments more than 100 million years ago
during the Mesozoic Era. Newly formed streams, which flowed
southeastward following the seaward slope of the land, cut their
drainage inland from the Atlantic Ocean. Following a lengthy
period of erosion, the underlying folded and faulted rocks of the
Appalachians were exposed and streams began to adjust to the
rock’s structure. Water gaps were eroded in places where southeast
flowing rivers first encountered the resistant rocks that make up
the modern uplands such as Kittatinny Mountain.
12 The principal landscape features of the park probably formed
during the late Tertiary period (10 to 25 million years ago). During
this time, erosion and valley cutting accelerated when sea level fell
due to the growth of the Antarctic ice sheet, and possible uplift
of the earth’s crust. Rejuvenated streams eroded the old land
surface, deepening valleys and water gaps and further adjusting
their courses along belts of weak rock. It was probably during
this time that a stream flowing in what is now Culvers Gap was
intercepted and captured by a tributary of the Delaware River. THE ICE AGE
During the Pleistocene Epoch (2 million to 10 thousand years
ago) ice sheets adv...
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