Williamsport, Pennsylvania
Williamsport is a city in, the county seat of, Lycoming County, United States. In 2017, the population was estimated at 28,462, it is the principal city of the Williamsport, Pennsylvania Metropolitan Statistical Area, which has a population of about 114,000. The city is the cultural and commercial center of Central Pennsylvania, it is 131 miles from Philadelphia, 166 miles from Pittsburgh and 85 miles from state capital Harrisburg. The city is renowned for arts scene and food. Williamsport was settled by Americans late in the 18th century, the town began to prosper due to its lumber industry. By the early 20th century, the town reached the height of its prosperity and the population has since declined by about a third from its peak of around 45,000 in 1950. Williamsport is the birthplace of Little League Baseball. South Williamsport, a town nearby, is the headquarters of Little League Baseball and annually hosts the Little League World Series in late summer. Colonial settlement in what is today Williamsport dates back to 1786 but the area was inhabited by the Iroquois.
Williamsport was incorporated as a borough on March 1, 1806, as a city on January 15, 1866. In the late 19th century, Williamsport was known as "The Lumber Capital of the World" because of its thriving lumber industry; the city is the original home of Little League Baseball, founded in 1939 as a three-team league. Following World War II the city's population and economic prosperity have declined. In 1763 the Battle of Muncy Hills took place during the French and Indian War, it was a clash between the Native Americans and colonists seeking homestead sites in Native American territory. In 1768, at the Treaty of Fort Stanwix, the British purchased the land that became Lycoming County from the Iroquois Nation who controlled the lands. In 1786 the first house was built in Williamsport. James Russell built his inn on what is now the northeast corner of East Third and Mulberry Streets in downtown. On April 13, 1795 Lycoming County was formed from Northumberland County, it encompassed all the lands of Northumberland County situated west of Muncy Hills and was a domain of 12,500 square miles, comprising most of north central Pennsylvania.
In 1796 the first recorded childbirth in Williamsport was James Russell the son of Mr. and Mrs. William Russell and grandson of James Russell of the Russell Inn and the first school was built as a one-room log addition to the building that would become the first Lycoming County Courthouse. In 1798 the first brick house in Williamsport was erected on Front Street, between Market and Mulberry, by Andrew Tulloh, a lawyer; the bricks were made on the banks of Grafius Run. In 1799, a post office opened at the corner of Third and State Streets in what is now downtown, the following year, a jail was constructed at the northeast corner of William and Third Streets; the post office was converted to a saloon,In 1801 the town's first store was opened by William Winter on Third Street. In 1831 Jacob L. Mussina established the Repasz Band, the oldest brass band in America still in existence. On Oct. 15 1834 The West Branch Canal opened and the first boat to pass through the canal en route to Jersey Shore was that of George Aughenbaugh.
The first freight carried into town was iron for the foundry of John B. Hall; the same year the enactment of the common school law by Pennsylvania Legislature led to public education here. In May 1835, the first public schools opened in Williamsport and the town's first bank, the West Branch National Bank; the Underground Railroad, used by enslaved African-Americans to obtain their freedom in the 30 years before the Civil War included routes from states in the South, which supported slavery, to "free" states in the North and Canada. From 1830 until 1865, the underground railroad, a system of safe houses and routes for slaves escaping to freedom, operated in Lycoming County. Based on the oral history of Mamie Sweeting Diggs, fourth generation descent and great-granddaughter, was a river raftsman on the Susquehanna river who had migrated from Oswego, New York, he lived on the Muncy Indian Reservation. During his trips transporting logs to Maryland, he brought escaped slaves back on foot from Baltimore, over Bald Eagle Mountain and hid them at his home and in the caves on Freedom Road.
Mamie's grandfather, helped his father, Daniel Hughes, hide escaped slaves in the caves behind their home on Freedom Road. They fed them, nursed the sick back to health and delivered them safely to the next "station", The Apker House in Trout Run; the Apker House was the home of Robert Fairies and president of the Williamsport-Elmira Railroad. The railroad ran through his property where escaped slaves were hidden in the barn and house and loaded into railway baggage cars for the trip to Elmira, NY, the next "station."Mamie's grandfather, Robert passed the stories to his children, including Mamie's mother, Marion. Marion tended the family homestead, maintained Freedom Road Cemetery and passed Daniel's stories down to her children. In 1849 the Market Street Bridge was built over the West Branch Susquehanna River, it was opened as a toll bridge to cover the state's costs of $23,797. In 1854 a brewery opened; the brewery was sold to Henry Flock in 1865. This brewery was run by the Flock family until the 1940s.
The Flock's business survived Prohibition by converting to a dairy. In 1875, the first tower clock in the United States to sound the Cambridge Quarters was installed at Trinity Episcopal Chur
Atlantic Ocean
The Atlantic Ocean is the second largest of the world's oceans, with an area of about 106,460,000 square kilometers. It covers 20 percent of the Earth's surface and about 29 percent of its water surface area, it separates the "Old World" from the "New World". The Atlantic Ocean occupies an elongated, S-shaped basin extending longitudinally between Europe and Africa to the east, the Americas to the west; as one component of the interconnected global ocean, it is connected in the north to the Arctic Ocean, to the Pacific Ocean in the southwest, the Indian Ocean in the southeast, the Southern Ocean in the south. The Equatorial Counter Current subdivides it into the North Atlantic Ocean and the South Atlantic Ocean at about 8°N. Scientific explorations of the Atlantic include the Challenger expedition, the German Meteor expedition, Columbia University's Lamont-Doherty Earth Observatory and the United States Navy Hydrographic Office; the oldest known mentions of an "Atlantic" sea come from Stesichorus around mid-sixth century BC: Atlantikoi pelágei and in The Histories of Herodotus around 450 BC: Atlantis thalassa where the name refers to "the sea beyond the pillars of Heracles", said to be part of the sea that surrounds all land.
Thus, on one hand, the name refers to Atlas, the Titan in Greek mythology, who supported the heavens and who appeared as a frontispiece in Medieval maps and lent his name to modern atlases. On the other hand, to early Greek sailors and in Ancient Greek mythological literature such as the Iliad and the Odyssey, this all-encompassing ocean was instead known as Oceanus, the gigantic river that encircled the world. In contrast, the term "Atlantic" referred to the Atlas Mountains in Morocco and the sea off the Strait of Gibraltar and the North African coast; the Greek word thalassa has been reused by scientists for the huge Panthalassa ocean that surrounded the supercontinent Pangaea hundreds of millions of years ago. The term "Aethiopian Ocean", derived from Ancient Ethiopia, was applied to the Southern Atlantic as late as the mid-19th century. During the Age of Discovery, the Atlantic was known to English cartographers as the Great Western Ocean; the term The Pond is used by British and American speakers in context to the Atlantic Ocean, as a form of meiosis, or sarcastic understatement.
The term dates to as early as 1640, first appearing in print in pamphlet released during the reign of Charles I, reproduced in 1869 in Nehemiah Wallington's Historical Notices of Events Occurring Chiefly in The Reign of Charles I, where "great Pond" is used in reference to the Atlantic Ocean by Francis Windebank, Charles I's Secretary of State. The International Hydrographic Organization defined the limits of the oceans and seas in 1953, but some of these definitions have been revised since and some are not used by various authorities and countries, see for example the CIA World Factbook. Correspondingly, the extent and number of oceans and seas varies; the Atlantic Ocean is bounded on the west by South America. It connects to the Arctic Ocean through the Denmark Strait, Greenland Sea, Norwegian Sea and Barents Sea. To the east, the boundaries of the ocean proper are Europe: the Strait of Africa. In the southeast, the Atlantic merges into the Indian Ocean; the 20° East meridian, running south from Cape Agulhas to Antarctica defines its border.
In the 1953 definition it extends south to Antarctica, while in maps it is bounded at the 60° parallel by the Southern Ocean. The Atlantic has irregular coasts indented by numerous bays and seas; these include the Baltic Sea, Black Sea, Caribbean Sea, Davis Strait, Denmark Strait, part of the Drake Passage, Gulf of Mexico, Labrador Sea, Mediterranean Sea, North Sea, Norwegian Sea all of the Scotia Sea, other tributary water bodies. Including these marginal seas the coast line of the Atlantic measures 111,866 km compared to 135,663 km for the Pacific. Including its marginal seas, the Atlantic covers an area of 106,460,000 km2 or 23.5% of the global ocean and has a volume of 310,410,900 km3 or 23.3% of the total volume of the earth's oceans. Excluding its marginal seas, the Atlantic covers 81,760,000 km2 and has a volume of 305,811,900 km3; the North Atlantic covers 41,490,000 km2 and the South Atlantic 40,270,000 km2. The average depth is 3,646 m and the maximum depth, the Milwaukee Deep in the Puerto Rico Trench, is 8,486 m.
The bathymetry of the Atlantic is dominated by a submarine mountain range called the Mid-Atlantic Ridge. It runs from 87°N or 300 km south of the North Pole to the subantarctic Bouvet Island at 42°S; the MAR divides the Atlantic longitudinally into two halves, in each of which a series of basins are delimited by secondary, transverse ridges. The MAR reaches above 2,000 m along most of its length, but is interrupted by larger transform faults at two places: the Romanche Trench near the Equator and the Gibbs Fracture Zone at 53°N; the MAR is a barrier for bottom water, but at these two transform faults deep water currents can pass from one side to the othe
Pennsylvania
Pennsylvania the Commonwealth of Pennsylvania, is a state located in the northeastern and Mid-Atlantic regions of the United States. The Appalachian Mountains run through its middle; the Commonwealth is bordered by Delaware to the southeast, Maryland to the south, West Virginia to the southwest, Ohio to the west, Lake Erie and the Canadian province of Ontario to the northwest, New York to the north, New Jersey to the east. Pennsylvania is the 33rd-largest state by area, the 6th-most populous state according to the most recent official U. S. Census count in 2010, it is the 9th-most densely populated of the 50 states. Pennsylvania's two most populous cities are Philadelphia, Pittsburgh; the state capital and its 10th largest city is Harrisburg. Pennsylvania has 140 miles of waterfront along the Delaware Estuary; the state is one of the 13 original founding states of the United States. Part of Pennsylvania, together with the present State of Delaware, had earlier been organized as the Colony of New Sweden.
It was the second state to ratify the United States Constitution, on December 12, 1787. Independence Hall, where the United States Declaration of Independence and United States Constitution were drafted, is located in the state's largest city of Philadelphia. During the American Civil War, the Battle of Gettysburg was fought in the south central region of the state. Valley Forge near Philadelphia was General Washington's headquarters during the bitter winter of 1777–78. Pennsylvania is 170 miles north to south and 283 miles east to west. Of a total 46,055 square miles, 44,817 square miles are land, 490 square miles are inland waters, 749 square miles are waters in Lake Erie, it is the 33rd-largest state in the United States. Pennsylvania has 51 miles of coastline along Lake Erie and 57 miles of shoreline along the Delaware Estuary. Of the original Thirteen Colonies, Pennsylvania is the only state that does not border the Atlantic Ocean; the boundaries of the state are the Mason–Dixon line to the south, the Twelve-Mile Circle on the Pennsylvania-Delaware border, the Delaware River to the east, 80° 31' W to the west and the 42° N to the north, with the exception of a short segment on the western end, where a triangle extends north to Lake Erie.
Cities include Philadelphia, Reading and Lancaster in the southeast, Pittsburgh in the southwest, the tri-cities of Allentown and Easton in the central east. The northeast includes the former anthracite coal mining cities of Scranton, Wilkes-Barre and Hazleton. Erie is located in the northwest. State College serves the central region while Williamsport serves the commonwealth's north-central region as does Chambersburg the south-central region, with York and the state capital Harrisburg on the Susquehanna River in the east-central region of the Commonwealth and Altoona and Johnstown in the west-central region; the state has five geographical regions, namely the Allegheny Plateau and Valley, Atlantic Coastal Plain and the Erie Plain. New York Ontario Maryland Delaware West Virginia New Jersey Ohio Pennsylvania's diverse topography produces a variety of climates, though the entire state experiences cold winters and humid summers. Straddling two major zones, the majority of the state, with the exception of the southeastern corner, has a humid continental climate.
The southern portion of the state has a humid subtropical climate. The largest city, has some characteristics of the humid subtropical climate that covers much of Delaware and Maryland to the south. Summers are hot and humid. Moving toward the mountainous interior of the state, the winter climate becomes colder, the number of cloudy days increases, snowfall amounts are greater. Western areas of the state locations near Lake Erie, can receive over 100 inches of snowfall annually, the entire state receives plentiful precipitation throughout the year; the state may be subject to severe weather from spring through summer into fall. Tornadoes occur annually in the state, sometimes in large numbers, such as 30 recorded tornadoes in 2011; as of 1600, the tribes living in Pennsylvania were the Algonquian Lenape, the Iroquoian Susquehannock & Petun and the Siouan Monongahela Culture, who may have been the same as a little known tribe called the Calicua, or Cali. Other tribes who entered the region during the colonial era were the Trockwae, Saponi, Nanticoke, Conoy Piscataway, Iroquois Confederacy—possibly among others.
Other tribes, like the Erie, may have once held some land in Pennsylvania, but no longer did so by the year 1600. Both the Dutch and the English claimed both sides of the Delaware River as part of their colonial lands in America; the Dutch were the first to take possession. By June 3, 1631, the Dutch had begun settling the Delmarva Peninsula by establishing the Zwaanendael Colony on the site of present-day Lewes, Delaware. In 1638, Sweden established the New Sweden Colony, in the region of Fort Christina, on the site of present-day Wilmington, Delaware. New Sweden claimed and, for the most part, controlled the lower Delaware River region (parts of present-day Delaware, New Jersey, Pe
Appalachian Mountains
The Appalachian Mountains called the Appalachians, are a system of mountains in eastern North America. The Appalachians first formed 480 million years ago during the Ordovician Period, they once reached elevations similar to those of the Alps and the Rocky Mountains before experiencing natural erosion. The Appalachian chain is a barrier to east–west travel, as it forms a series of alternating ridgelines and valleys oriented in opposition to most highways and railroads running east–west. Definitions vary on the precise boundaries of the Appalachians; the United States Geological Survey defines the Appalachian Highlands physiographic division as consisting of thirteen provinces: the Atlantic Coast Uplands, Eastern Newfoundland Atlantic, Maritime Acadian Highlands, Maritime Plain, Notre Dame and Mégantic Mountains, Western Newfoundland Mountains, Blue Ridge and Ridge, Saint Lawrence Valley, Appalachian Plateaus, New England province, the Adirondack areas. A common variant definition does not include the Adirondack Mountains, which geologically belong to the Grenville Orogeny and have a different geological history from the rest of the Appalachians.
The mountain range is in the United States but it extends into southeastern Canada, forming a zone from 100 to 300 mi wide, running from the island of Newfoundland 1,500 mi southwestward to Central Alabama in the United States. The range covers parts of the islands of Saint Pierre and Miquelon, which comprise an overseas territory of France; the system is divided into a series of ranges, with the individual mountains averaging around 3,000 ft. The highest of the group is Mount Mitchell in North Carolina at 6,684 feet, the highest point in the United States east of the Mississippi River; the term Appalachian refers to several different regions associated with the mountain range. Most broadly, it refers to the entire mountain range with its surrounding hills and the dissected plateau region; the term is used more restrictively to refer to regions in the central and southern Appalachian Mountains including areas in the states of Kentucky, Virginia, West Virginia, North Carolina, as well as sometimes extending as far south as northern Alabama and western South Carolina, as far north as Pennsylvania, southern Ohio, parts of southern upstate New York.
The Ouachita Mountains in Arkansas and Oklahoma were part of the Appalachians as well but became disconnected through geologic history. While exploring inland along the northern coast of Florida in 1528, the members of the Narváez expedition, including Álvar Núñez Cabeza de Vaca, found a Native American village near present-day Tallahassee, Florida whose name they transcribed as Apalchen or Apalachen; the name was soon altered by the Spanish to Apalachee and used as a name for the tribe and region spreading well inland to the north. Pánfilo de Narváez's expedition first entered Apalachee territory on June 15, 1528, applied the name. Now spelled "Appalachian," it is the fourth-oldest surviving European place-name in the US. After the de Soto expedition in 1540, Spanish cartographers began to apply the name of the tribe to the mountains themselves; the first cartographic appearance of Apalchen is on Diego Gutierrez's map of 1562. The name was not used for the whole mountain range until the late 19th century.
A competing and more popular name was the "Allegheny Mountains", "Alleghenies", "Alleghania". In the early 19th century, Washington Irving proposed renaming the United States either Appalachia or Alleghania. In U. S. dialects in the southern regions of the Appalachians, the word is pronounced, with the third syllable sounding like "latch". In northern parts of the mountain range, it is pronounced or. There is great debate between the residents of the regions as to which pronunciation is the more correct one. Elsewhere, a accepted pronunciation for the adjective Appalachian is, with the last two syllables "-ian" pronounced as in the word "Romanian"; the whole system may be divided into three great sections: Northern: The northern section runs from the Canadian province of Newfoundland and Labrador to the Hudson River. It includes the Long Range Mountains and Annieopsquotch Mountains on the island of Newfoundland, Chic-Choc Mountains and Notre Dame Range in Quebec and New Brunswick, scattered elevations and small ranges elsewhere in Nova Scotia and New Brunswick, the Longfellow Mountains in Maine, the White Mountains in New Hampshire, the Green Mountains in Vermont, The Berkshires in Massachusetts and Connecticut.
The Metacomet Ridge Mountains in Connecticut and south-central Massachusetts, although contained within the Appalachian province, is a younger system and not geologically associated with the Appalachians. The Monteregian Hills, which cross the Green Mountains in Quebec, are unassociated with the Appalachians. Central: The central section goes from the Hudson Valley to the New River running through Virginia and West Virginia, it comprises the Valley Ridges between the Allegheny Front of the Allegheny Plateau and the Great Appalachian Valley, the New York–New Jersey Highlands, the Taconic Mountains in New York, a large portion of the Blue Ridge. Southern: The southern section runs from the New River onwards, it consists of the prolongation of the Blue Ridge, divided into the Western Blue Ridge Front and the Eastern Blue Ridge Front, the Ridge-and-Valley Appalachians, the Cumberland Plateau. The Adirondack Mountains in New Y
Permian
The Permian is a geologic period and system which spans 47 million years from the end of the Carboniferous Period 298.9 million years ago, to the beginning of the Triassic period 251.902 Mya. It is the last period of the Paleozoic era; the concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the city of Perm. The Permian witnessed the diversification of the early amniotes into the ancestral groups of the mammals, turtles and archosaurs; the world at the time was dominated by two continents known as Pangaea and Siberia, surrounded by a global ocean called Panthalassa. The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior. Amniotes, who could better cope with these drier conditions, rose to dominance in place of their amphibian ancestors; the Permian ended with the Permian–Triassic extinction event, the largest mass extinction in Earth's history, in which nearly 96% of marine species and 70% of terrestrial species died out.
It would take well into the Triassic for life to recover from this catastrophe. Recovery from the Permian–Triassic extinction event was protracted; the term "Permian" was introduced into geology in 1841 by Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Édouard de Verneuil; the region now lies in the Perm Krai of Russia. Official ICS 2017 subdivisions of the Permian System from most recent to most ancient rock layers are: Lopingian epoch Changhsingian Wuchiapingian Others: Waiitian Makabewan Ochoan Guadalupian epoch Capitanian stage Wordian stage Roadian stage Others: Kazanian or Maokovian Braxtonian stage Cisuralian epoch Kungurian stage Artinskian stage Sakmarian stage Asselian stage Others: Telfordian Mangapirian Sea levels in the Permian remained low, near-shore environments were reduced as all major landmasses collected into a single continent—Pangaea; this could have in part caused the widespread extinctions of marine species at the end of the period by reducing shallow coastal areas preferred by many marine organisms.
During the Permian, all the Earth's major landmasses were collected into a single supercontinent known as Pangaea. Pangaea straddled the equator and extended toward the poles, with a corresponding effect on ocean currents in the single great ocean, the Paleo-Tethys Ocean, a large ocean that existed between Asia and Gondwana; the Cimmeria continent rifted away from Gondwana and drifted north to Laurasia, causing the Paleo-Tethys Ocean to shrink. A new ocean was growing on its southern end, the Tethys Ocean, an ocean that would dominate much of the Mesozoic era. Large continental landmass interiors experience climates with extreme variations of heat and cold and monsoon conditions with seasonal rainfall patterns. Deserts seem to have been widespread on Pangaea; such dry conditions favored gymnosperms, plants with seeds enclosed in a protective cover, over plants such as ferns that disperse spores in a wetter environment. The first modern trees appeared in the Permian. Three general areas are noted for their extensive Permian deposits—the Ural Mountains and the southwest of North America, including the Texas red beds.
The Permian Basin in the U. S. states of Texas and New Mexico is so named because it has one of the thickest deposits of Permian rocks in the world. The climate in the Permian was quite varied. At the start of the Permian, the Earth was still in an ice age. Glaciers receded around the mid-Permian period as the climate warmed, drying the continent's interiors. In the late Permian period, the drying continued although the temperature cycled between warm and cool cycles. Permian marine deposits are rich in fossil mollusks and brachiopods. Fossilized shells of two kinds of invertebrates are used to identify Permian strata and correlate them between sites: fusulinids, a kind of shelled amoeba-like protist, one of the foraminiferans, ammonoids, shelled cephalopods that are distant relatives of the modern nautilus. By the close of the Permian, trilobites and a host of other marine groups became extinct. Terrestrial life in the Permian included diverse plants, fungi and various types of tetrapods; the period saw a massive desert covering the interior of Pangaea.
The warm zone spread in the northern hemisphere. The rocks formed at that time were stained red by iron oxides, the result of intense heating by the sun of a surface devoid of vegetation cover. A number of older types of plants and animals became marginal elements; the Permian began with the Carboniferous flora still flourishing. About the middle of the Permian a major transition in vegetation began; the swamp-loving
Sediment
Sediment is a occurring material, broken down by processes of weathering and erosion, is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example and silt can be carried in suspension in river water and on reaching the sea bed deposited by sedimentation and if buried, may become sandstone and siltstone. Sediments are most transported by water, but wind and glaciers. Beach sands and river channel deposits are examples of fluvial transport and deposition, though sediment often settles out of slow-moving or standing water in lakes and oceans. Desert sand dunes and loess are examples of aeolian deposition. Glacial moraine deposits and till are ice-transported sediments. Sediment can be classified based on its grain composition. Sediment size is measured on a log base 2 scale, called the "Phi" scale, which classifies particles by size from "colloid" to "boulder". Composition of sediment can be measured in terms of: parent rock lithology mineral composition chemical make-up.
This leads to an ambiguity in which clay can be used as a composition. Sediment is transported based on the strength of the flow that carries it and its own size, volume and shape. Stronger flows will increase the lift and drag on the particle, causing it to rise, while larger or denser particles will be more to fall through the flow. Rivers and streams carry sediment in their flows; this sediment can be in a variety of locations within the flow, depending on the balance between the upwards velocity on the particle, the settling velocity of the particle. These relationships are shown in the following table for the Rouse number, a ratio of sediment fall velocity to upwards velocity. Rouse = Settling velocity Upwards velocity from lift and drag = w s κ u ∗ where w s is the fall velocity κ is the von Kármán constant u ∗ is the shear velocity If the upwards velocity is equal to the settling velocity, sediment will be transported downstream as suspended load. If the upwards velocity is much less than the settling velocity, but still high enough for the sediment to move, it will move along the bed as bed load by rolling and saltating.
If the upwards velocity is higher than the settling velocity, the sediment will be transported high in the flow as wash load. As there are a range of different particle sizes in the flow, it is common for material of different sizes to move through all areas of the flow for given stream conditions. Sediment motion can create self-organized structures such as ripples, dunes, or antidunes on the river or stream bed; these bedforms are preserved in sedimentary rocks and can be used to estimate the direction and magnitude of the flow that deposited the sediment. Overland flow can transport them downslope; the erosion associated with overland flow may occur through different methods depending on meteorological and flow conditions. If the initial impact of rain droplets dislodges soil, the phenomenon is called rainsplash erosion. If overland flow is directly responsible for sediment entrainment but does not form gullies, it is called "sheet erosion". If the flow and the substrate permit channelization, gullies may form.
The major fluvial environments for deposition of sediments include: Deltas Point bars Alluvial fans Braided rivers Oxbow lakes Levees Waterfalls Wind results in the transportation of fine sediment and the formation of sand dune fields and soils from airborne dust. Glaciers carry a wide range of sediment sizes, deposit it in moraines; the overall balance between sediment in transport and sediment being deposited on the bed is given by the Exner equation. This expression states that the rate of increase in bed elevation due to deposition is proportional to the amount of sediment that falls out of the flow; this equation is important in that changes in the power of the flow change the ability of the flow to carry sediment, this is reflected in the patterns of erosion and deposition observed throughout a stream. This can be localized, due to small obstacles. Erosion and deposition can be regional. Deposition can occur due to dam emplacement that causes the river to pool and deposit its entire load, or due to base level rise.
Seas and lakes accumulate sediment over time. The sediment can consist of terrigenous material, which originates on land, but may be deposited in either terrestrial, marine, or lacustrine environments, or of sediments originating in the body of water. Terrigenous material is supplied by nearby rivers and streams or reworked marine sediment. In the mid-ocean, the exoskeletons of dead organisms are responsible for sediment accumulation. Deposited sediments are the source of sedimentary rocks, which can contain fossils of
This article incorporates public domain material from the National Park Service document "Geology of Manassas National Battlefield Park".
This article incorporates