Geology Of Delaware
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Geology Of Delaware
The geology of Delaware consists of two physiographic provinces located in the U.S. state of Delaware. They are the Atlantic Coastal Plain and the Piedmont. Coastal plain The coastal plain in Delaware is by far the largest province, encompassing all of the state south of the Kirkwood Highway from Newark to Wilmington. The unconsolidated sediments of the coastal plain range in age from Cretaceous to recent. They consist of gravels, sands, silt, and clay, with varying mixtures of all four. The oldest layer, the Potomac Formation also contains some scattered lignite. As recently as five million years ago, much of present-day Delaware was submerged as the floor of a shallow sea, the Salisbury Embayment; only with the retreat of global sea levels in recent geologic times did the coastal plain areas of the state emerge as dry land. Atlantic coastline Delaware has a 25-mile (40 km) coastline that includes the communities of Rehoboth Beach, Dewey Beach, Bethany Beach, Sout ...
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Headlands
A headland, also known as a head, is a coastal landform, a point of land usually high and often with a sheer drop, that extends into a body of water. It is a type of promontory. A headland of considerable size often is called a cape.Whittow, John (1984). ''Dictionary of Physical Geography''. London: Penguin, 1984, pp. 80, 246. . Headlands are characterised by high, breaking waves, rocky shores, intense erosion, and steep sea cliff. Headlands and bays are often found on the same coastline. A bay is flanked by land on three sides, whereas a headland is flanked by water on three sides. Headlands and bays form on discordant coastlines, where bands of rock of alternating resistance run perpendicular to the coast. Bays form when weak (less resistant) rocks (such as sands and clays) are eroded, leaving bands of stronger (more resistant) rocks (such as chalk, limestone, and granite) forming a headland, or peninsula. Through the deposition of sediment within the bay and the erosion of ...
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Ordovician
The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. The Ordovician, named after the Celtic Britons, Welsh tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same Rock (geology), rock beds in North Wales in the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed Stratum, strata were different from those of either the Cambrian or the Silurian systems, and placed them in a system of their own. The Ordovician received international approval in 1960 (forty years after Lapworth's death), when it was adopted as an official period of the Paleozoic Era by the International Union of Geological Sciences, Intern ...
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Cambrian
The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago (mya) to the beginning of the Ordovician Period mya. Its subdivisions, and its base, are somewhat in flux. The period was established as "Cambrian series" by Adam Sedgwick, who named it after Cambria, the Latin name for 'Cymru' (Wales), where Britain's Cambrian rocks are best exposed. Sedgwick identified the layer as part of his task, along with Roderick Murchison, to subdivide the large "Transition Series", although the two geologists disagreed for a while on the appropriate categorization. The Cambrian is unique in its unusually high proportion of sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Ca ...
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Precambrian
The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic Eon, which is named after Cambria, the Latinised name for Wales, where rocks from this age were first studied. The Precambrian accounts for 88% of the Earth's geologic time. The Precambrian is an informal unit of geologic time, subdivided into three eons ( Hadean, Archean, Proterozoic) of the geologic time scale. It spans from the formation of Earth about 4.6 billion years ago ( Ga) to the beginning of the Cambrian Period, about million years ago ( Ma), when hard-shelled creatures first appeared in abundance. Overview Relatively little is known about the Precambrian, despite it making up roughly seven-eighths of the Earth's history, and what is known has largely been discovered from the 1960s onwards. The Precambrian fossil ...
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Maryland
Maryland ( ) is a state in the Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware and the Atlantic Ocean to its east. Baltimore is the largest city in the state, and the capital is Annapolis. Among its occasional nicknames are '' Old Line State'', the ''Free State'', and the '' Chesapeake Bay State''. It is named after Henrietta Maria, the French-born queen of England, Scotland, and Ireland, who was known then in England as Mary. Before its coastline was explored by Europeans in the 16th century, Maryland was inhabited by several groups of Native Americans – mostly by Algonquian peoples and, to a lesser degree, Iroquoian and Siouan. As one of the original Thirteen Colonies of England, Maryland was founded by George Calvert, 1st Baron Baltimore, a Catholic convert"George Calvert and Cecilius Calvert, Barons Baltimore" William Hand Browne, ...
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Pennsylvania
Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, Maryland to its south, West Virginia to its southwest, Ohio to its west, Lake Erie and the Canadian province of Ontario to its northwest, New York to its north, and the Delaware River and New Jersey to its east. Pennsylvania is the fifth-most populous state in the nation with over 13 million residents as of 2020. It is the 33rd-largest state by area and ranks ninth among all states in population density. The southeastern Delaware Valley metropolitan area comprises and surrounds Philadelphia, the state's largest and nation's sixth most populous city. Another 2.37 million reside in Greater Pittsburgh in the southwest, centered around Pittsburgh, the state's second-largest and Western Pennsylvania's largest city. The state's su ...
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Ice Age
An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and greenhouse periods, during which there are no glaciers on the planet. Earth is currently in the Quaternary glaciation. Individual pulses of cold climate within an ice age are termed ''glacial periods'' (or, alternatively, ''glacials, glaciations, glacial stages, stadials, stades'', or colloquially, ''ice ages''), and intermittent warm periods within an ice age are called '' interglacials'' or ''interstadials''. In glaciology, ''ice age'' implies the presence of extensive ice sheets in both northern and southern hemispheres. By this definition, Earth is currently in an interglacial period—the Holocene. The amount of anthropogenic greenhouse gases emitted into Earth's oceans and atmosphere is predicted to prevent the next glacial period for th ...
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Delaware River
The Delaware River is a major river in the Mid-Atlantic (United States), Mid-Atlantic region of the United States. From the meeting of its branches in Hancock (village), New York, Hancock, New York, the river flows for along the borders of New York (state), New York, Pennsylvania, New Jersey, and Delaware, before emptying into Delaware Bay. It is the longest free-flowing river in the Eastern United States. The river has been recognized by the National Wildlife Federation as one of the country's Great Waters. The river's drainage basin, watershed drains an area of and provides drinking water for 17 million people. The river has two branches that rise in the Catskill Mountains of New York: the West Branch Delaware River, West Branch at Mount Jefferson (New York), Mount Jefferson in Jefferson, New York, Jefferson, Schoharie County, New York, Schoharie County, and the East Branch Delaware River, East Branch at Grand Gorge, New York, Grand Gorge, Delaware County, New York, ...
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Ocean City, Maryland
Ocean City, officially the Town of Ocean City, is an Atlantic Ocean, Atlantic resort town in Worcester County, Maryland, Worcester County, Maryland along the East Coast of the United States. The population was 6,844 at the 2020 United States census, 2020 U.S. census, although during summer weekends the city hosts between 320,000 and 345,000 vacationers, and up to 8 million visitors annually. During the summer, Ocean City becomes the second most populated municipality in Maryland, after Baltimore. To the north of Ocean City is Fenwick Island (Delaware–Maryland), Fenwick Island, it is part of the Salisbury, MD-DE Metropolitan Statistical Area, as defined by the United States Census Bureau. History The land upon which the city was built, as well as much of the surrounding area, was obtained by Englishman Thomas Fenwick from the Native Americans. In 1869, businessman Isaac Coffin built the first beach-front cottage to receive paying guests. During those days, people arrived by stag ...
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Longshore Drift
Longshore drift from longshore current is a geological process that consists of the transportation of sediments (clay, silt, pebbles, sand, shingle) along a coast parallel to the shoreline, which is dependent on the angle incoming wave direction. Oblique incoming wind squeezes water along the coast, and so generates a water current which moves parallel to the coast. Longshore drift is simply the sediment moved by the longshore current. This current and sediment movement occur within the surf zone. The process is also known as littoral drift. Beach sand is also moved on such oblique wind days, due to the swash and backwash of water on the beach. Breaking surf sends water up the beach (swash) at an oblique angle and gravity then drains the water straight downslope (backwash) perpendicular to the shoreline. Thus beach sand can move downbeach in a sawtooth fashion many tens of meters (yards) per day. This process is called "beach drift" but some workers regard it as simply part o ...
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Bar (landform)
In oceanography, geomorphology, and geoscience, a shoal is a natural submerged ridge, bank, or bar that consists of, or is covered by, sand or other unconsolidated material and rises from the bed of a body of water to near the surface. It often refers to those submerged ridges, banks, or bars that rise near enough to the surface of a body of water as to constitute a danger to navigation. Shoals are also known as sandbanks, sandbars, or gravelbars. Two or more shoals that are either separated by shared troughs or interconnected by past or present sedimentary and hydrographic processes are referred to as a shoal complex.Neuendorf, K.K.E., J.P. Mehl Jr., and J.A. Jackson, eds. (2005) ''Glossary of Geology'' (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. The term ''shoal'' is also used in a number of ways that can be either similar or quite different from how it is used in geologic, geomorphic, and oceanographic literature. Sometimes, this term refe ...
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