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14-573: The Atlantic Seaboard Fall Line , or Fall Zone , is a 900-mile (1,400 km) escarpment where the Piedmont and Atlantic coastal plain meet in the eastern United States . Much of the Atlantic Seaboard fall line passes through areas where no evidence of faulting is present. The fall line marks the geologic boundary of hard metamorphosed terrain—the product of the Taconic orogeny —and
28-460: A fault displaces the ground surface so that one side is higher than the other, a fault scarp is created. This can occur in dip-slip faults , or when a strike-slip fault brings a piece of high ground adjacent to an area of lower ground. Earth is not the only planet where escarpments occur. They are believed to occur on other planets when the crust contracts , as a result of cooling. On other Solar System bodies such as Mercury , Mars , and
42-430: A presumed continuous granite ridge, rising about one hundred and thirty feet above tide water. That ridge from New York to James River inclusively arrests the ascent of the tide; the falls of every river within that space being precisely at the head of the tide; pursuing thence southwardly a direction nearly parallel to the mountains, it recedes from the sea, leaving in each southern river an extent of good navigation between
56-569: The Moon , the Latin term rupes is used for an escarpment. When sedimentary beds are tilted and exposed to the surface, erosion and weathering may occur. Escarpments erode gradually and over geological time . The mélange tendencies of escarpments results in varying contacts between a multitude of rock types. These different rock types weather at different speeds, according to Goldich dissolution series so different stages of deformation can often be seen in
70-468: The base of the plateau . Scarps are generally formed by one of two processes: either by differential erosion of sedimentary rocks , or by movement of the Earth's crust at a geologic fault . The first process is the more common type: the escarpment is a transition from one series of sedimentary rocks to another series of a different age and composition. Escarpments are also frequently formed by faults. When
84-452: The fall-line cities. In 1808, Treasury Secretary Albert Gallatin noted the significance of the fall line as an obstacle to improved national communication and commerce between the Atlantic seaboard and the western river systems: The most prominent, though not perhaps the most insuperable obstacle in the navigation of the Atlantic rivers, consists in their lower falls, which are ascribed to
98-488: The fault scarp is very prone to erosion. This is especially true if the material being uplifted consists of unconsolidated sediment. Weathering, mass wasting, and water runoff can soon wear down these bluffs, sometimes resulting in V-shaped valleys along runoff channels. Adjacent V-shaped valley formations give the remaining fault spurs a very triangular shape. This formation is known as a triangular facet ; however, this landform
112-425: The fault. Differential movement and erosion may occur either along older inactive geologic faults, or recent active faults . Fault scarps often involve zones of highly fractured rock and discontinuities of hard and weak consistencies of rock. Bluffs can form from upthrown blocks and can be very steep, as in the case of Pakistan's coastal cliffs. The height of the scarp formation tends to be defined in terms of
126-411: The layers where the escarpments have been exposed to the elements. Fault scarp A fault scarp is a small step-like offset of the ground surface in which one side of a fault has shifted vertically in relation to the other. The topographic expression of fault scarps results from the differential erosion of rocks of contrasting resistance and the displacement of land surface by movement along
140-563: The sandy, relatively flat alluvial plain of the upper continental shelf, formed of unconsolidated Cretaceous and Cenozoic sediments . Examples of Fall Zone features include the Potomac River's Little Falls and the rapids in Richmond, Virginia , where the James River falls across a series of rapids down to its own tidal estuary. Before navigation improvements, such as locks, the fall line
154-689: The tide and the falls. Other falls of less magnitude are found at the gaps of the Blue Ridge , through which the rivers have forced their passage... Some cities that lie along the Piedmont–Coastal Plain fall line include the following (from north to south): Escarpment An escarpment is a steep slope or long cliff that forms as a result of faulting or erosion and separates two relatively level areas having different elevations . The terms scarp and scarp face are often used interchangeably with escarpment . Some sources differentiate
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#1732844204464168-439: The two terms, with escarpment referring to the margin between two landforms , and scarp referring to a cliff or a steep slope. In this usage an escarpment is a ridge which has a gentle slope on one side and a steep scarp on the other side. More loosely, the term scarp also describes a zone between a coastal lowland and a continental plateau which shows a marked, abrupt change in elevation caused by coastal erosion at
182-431: The vertical displacement along the fault. Active scarp faults may reflect rapid tectonic displacement and can be caused by any type of fault including strike-slip faults . Vertical displacement of ten meters may occur in fault scarps in volcanic bedrock, but is usually the result of multiple episodic movements of 5 to 10 meters per tectonic event. Due to the dramatic uplift along the fault, which exposes its surface,
196-401: Was generally the head of navigation on rivers due to their rapids or waterfalls, and the necessary portage around them. Numerous cities initially formed along the fall line because of the easy river transportation to seaports, as well the availability of water power to operate mills and factories, thus bringing together river traffic and industrial labor. U.S. Route 1 and I-95 link many of
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