Bioluminescence is the production and emission of light by a living organism. It is a form of chemiluminescence. Bioluminescence occurs in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some bioluminescent bacteria and terrestrial invertebrates such as fireflies. In some animals, a firefly squid has bioluminescence, the light is bacteriogenic, produced by symbiotic organisms such as Vibrio bacteria. In a general sense, the principal chemical reaction in bioluminescence involves some light-emitting molecule and an enzyme called the luciferin and the luciferase, respectively; because these are generic names, the luciferins and luciferases are distinguished by including the species or group, i.e. Firefly luciferin. In all characterized cases, the enzyme catalyzes the oxidation of the luciferin. In some species, the luciferase requires other cofactors, such as calcium or magnesium ions, sometimes the energy-carrying molecule adenosine triphosphate. In evolution, luciferins vary little: one in particular, coelenterazine, is found in eleven different animal, though in some of these, the animals obtain it through their diet.
Conversely, luciferases vary between different species, bioluminescence has arisen over forty times in evolutionary history. Both Aristotle and Pliny the Elder mentioned that damp wood sometimes gives off a glow and many centuries Robert Boyle showed that oxygen was involved in the process, both in wood and in glow-worms, it was not until the late nineteenth century. The phenomenon is distributed among animal groups in marine environments where dinoflagellates cause phosphorescence in the surface layers of water. On land it occurs in fungi and some groups of invertebrates, including insects; the uses of bioluminescence by animals include counter-illumination camouflage, mimicry of other animals, for example to lure prey, signalling to other individuals of the same species, such as to attract mates. In the laboratory, luciferase-based systems are used in genetic engineering and for biomedical research. Other researchers are investigating the possibility of using bioluminescent systems for street and decorative lighting, a bioluminescent plant has been created.
Before the development of the safety lamp for use in coal mines, dried fish skins were used in Britain and Europe as a weak source of light. This experimental form of illumination avoided the necessity of using candles which risked sparking explosions of firedamp. Another safe source of illumination in mines was bottles containing fireflies. In 1920, the American zoologist E. Newton Harvey published a monograph, The Nature of Animal Light, summarizing early work on bioluminescence. Harvey notes that Aristotle mentions light produced by dead fish and flesh, that both Aristotle and Pliny the Elder mention light from damp wood, he records that Robert Boyle experimented on these light sources, showed that both they and the glow-worm require air for light to be produced. Harvey notes that in 1753, J. Baker identified the flagellate Noctiluca "as a luminous animal" "just visible to the naked eye", in 1854 Johann Florian Heller identified strands of fungi as the source of light in dead wood. Tuckey, in his posthumous 1818 Narrative of the Expedition to the Zaire, described catching the animals responsible for luminescence.
He mentions pellucids and cancers. Under the microscope he described the "luminous property" to be in the brain, resembling "a most brilliant amethyst about the size of a large pin's head". Charles Darwin noticed bioluminescence in the sea, describing it in his Journal: While sailing in these latitudes on one dark night, the sea presented a wonderful and most beautiful spectacle. There was a fresh breeze, every part of the surface, which during the day is seen as foam, now glowed with a pale light; the vessel drove before her bows two billows of liquid phosphorus, in her wake she was followed by a milky train. As far as the eye reached, the crest of every wave was bright, the sky above the horizon, from the reflected glare of these livid flames, was not so utterly obscure, as over the rest of the heavens. Darwin observed a luminous "jelly-fish of the genus Dianaea" and noted that "When the waves scintillate with bright green sparks, I believe it is owing to minute crustacea, but there can be no doubt that many other pelagic animals, when alive, are phosphorescent."
He guessed that "a disturbed electrical condition of the atmosphere" was responsible. Daniel Pauly comments that Darwin "was lucky with most of his guesses, but not here", noting that biochemistry was too little known, that the complex evolution of the marine animals involved "would have been too much for comfort". Bioluminescence attracted the attention of the United States Navy in the Cold War, since submarines in some waters can create a bright enough wake to be detected; the navy was interested in predicting when such detection would be possible, hence guiding their own submarines to avoid detection. Among the anecdotes of navigation by bioluminescence, the Apollo 13 astronaut Jim Lovell recounted how as a navy pilot he had found his way back to his aircraft carrier USS Shangri-La when his navigation systems failed. Turning off his cabin lights, he saw the glowing wake of the ship, was able to fly to it and land safely; the French pharmacologist Raphaël Dubois carried out work on bioluminescen
Ithaca, New York
Ithaca is a city in the Finger Lakes region of New York. It is the seat of Tompkins County, as well as the largest community in the Ithaca–Tompkins County metropolitan area; this area contains the municipalities of the Town of Ithaca, the village of Cayuga Heights, other towns and villages in Tompkins County. The city of Ithaca is located on the southern shore of Cayuga Lake, in Central New York, about 45 miles south-west-west of Syracuse, it is named for the Greek island of Ithaca. Ithaca is home to Cornell University, an Ivy League school of over 20,000 students, most of whom study at its local campus. In addition, Ithaca College is a private, liberal arts college of over 7,000 students, located just south of the city in the Town of Ithaca, adding to the area's "college town" atmosphere. Nearby is Tompkins Cortland Community College; these three colleges bring tens of thousands of students, who increase Ithaca's seasonal population during the school year. The city's voters are notably more liberal than those in the remainder of Tompkins County or in upstate New York voting for Democratic Party candidates.
As of 2010, the city's population was 30,014. A 2017 census estimate stated the population was 31,006. Namgyal Monastery in Ithaca is the North American seat of the 14th Dalai Lama. Indigenous people occupied this area for thousands of years. At the time of European contact, this area was controlled by the Cayuga Nation, one of the powerful Five Nations of the Haudenosaunee or Iroquois League. Jesuit missionaries from New France are said to have had a mission to the Cayuga as early as 1657. Saponi and Tutelo peoples, Siouan-speaking tribes occupied lands at the south end of Cayuga Lake. Dependent tributaries of the Cayuga, they had been permitted to settle on the tribe's hunting lands at the south end of Cayuga Lake, as well as in Pony Hollow of what is known as present-day Newfield, New York. Remnants of these tribes had been forced from Virginia and North Carolina by tribal conflicts and European colonial encroachment; the Tuscarora people, an Iroquoian-speaking tribe from the Carolinas, migrated after defeat in the Yamasee War.
During the Revolutionary War, four of the six Iroquois nations were allied with the British, although bands made decisions on fighting in a decentralized way. Conflict with the rebel colonists was fierce throughout western New York. In retaliation for conflicts to the east, the 1779 Sullivan Expedition was conducted against the Iroquois peoples in the west of the state, destroying more than 40 villages and stored winter crops, it destroyed the Tutelo village of Coregonal, located near what is now the junction of state routes 13 and 13A just south of the Ithaca city limits. Most Iroquois were forced from the state after the Revolutionary War; the state sold off the former Iroquois lands to stimulate development and settlement by European Americans. Within the current boundaries of the City of Ithaca, Native Americans maintained only a temporary hunting camp at the base of Cascadilla Gorge. In 1788, eleven men from Kingston, New York came to the area with two Delaware people guides, to explore what they considered wilderness.
The following year Jacob Yaple, Isaac Dumond, Peter Hinepaw returned with their families and constructed log cabins. That same year Abraham Bloodgood of Albany obtained a patent from the state for 1,400 acres, which included all of the present downtown west of Tioga Street. In 1790, the federal government and state began an official program to grant land in the area, known as the Central New York Military Tract, as payment for service to the American soldiers of the Revolutionary War, as the government was cash poor. Most local land titles trace back to these Revolutionary war grants; as part of this process, the Central New York Military Tract, which included northern Tompkins County, was surveyed by Simeon De Witt, Bloodgood's son-in-law. De Witt was the nephew of Governor George Clinton; the Commissioners of Lands of New York State met in 1790. The Military Tract township in which proto-Ithaca was located was named the Town of Ulysses. A few years De Witt moved to Ithaca called variously "The Flats," "The City," or "Sodom".
Around 1791 De Witt sold them at modest prices. That same year John Yaple built a grist mill on Cascadilla Creek; the first frame house was erected in 1800 by Abram Markle. In 1804 the village had a postmaster, in 1805 a tavern. Ithaca became a transshipping point for salt from curing beds near Salina, New York to buyers south and east; this prompted construction in 1810 of the Owego Turnpike. When the War of 1812 cut off access to Nova Scotia gypsum, used for fertilizer, Ithaca became the center of trade in Cayuga gypsum; the Cayuga Steamboat Company was organized in 1819 and in 1820 launched the first steamboat on Cayuga Lake, the Enterprise. In 1821, the village was incorporated at the same time the Town of Ithaca was organized and separated from the parent Town of Ulysses. In 1834, the Ithaca and Owego Railroad's first horse-drawn train began service, connecting traffic on the east-west Erie Canal with the Susquehanna River to the south to expand the trade network
In geography, a plain is a flat, sweeping landmass that does not change much in elevation. Plains occur as lowlands along the bottoms of valleys or on the doorsteps of mountains, as coastal plains, as plateaus or uplands. In a valley, a plain is enclosed on two sides, but in other cases a plain may be delineated by a complete or partial ring of hills, by mountains, or by cliffs. Where a geological region contains more than one plain, they may be connected by a pass. Coastal plains would rise from sea level until they run into elevated features such as mountains or plateaus. Plains are one of the major landforms on earth, where they are present on all continents, would cover more than one-third of the world’s land area. Plains may have been formed from flowing lava, deposited by water, wind, or formed by erosion by these agents from hills and mountains. Plains would be under the grassland, savannah or tundra biomes. In a few instances and rainforests can be plains. Plains in many areas are important for agriculture because where the soils were deposited as sediments they may be deep and fertile, the flatness facilitates mechanization of crop production.
Depositional plains formed by the deposition of materials brought by various agents of transportation such as glaciers, rivers and wind. Their fertility and economic relevance depend on the types of sediments that are laid down; the types of depositional plains include: Abyssal plains, flat or gently sloping areas of the deep ocean basin. Planitia, the Latin word for plain, is used in the naming of plains on extraterrestrial objects, such as Hellas Planitia on Mars or Sedna Planitia on Venus. Alluvial plains, which are formed by rivers and which may be one of these overlapping types: Alluvial plains, formed over a long period of time by a river depositing sediment on their flood plains or beds, which become alluvial soil; the difference between a flood plain and an alluvial plain is: a flood plain represents areas experiencing flooding regularly in the present or whereas an alluvial plain includes areas where a flood plain is now and used to be, or areas which only experience flooding a few times a century.
Flood plain, adjacent to a lake, stream, or wetland that experiences occasional or periodic flooding. Scroll plain, a plain through which a river meanders with a low gradient. Glacial plains, formed by the movement of glaciers under the force of gravity: Outwash plain, a glacial out-wash plain formed of sediments deposited by melt-water at the terminus of a glacier. Sandar consist of stratified gravel and sand. Till plains, plain of glacial till that form when a sheet of ice becomes detached from the main body of a glacier and melts in place depositing the sediments it carries. Till plains are composed of unsorted material of all sizes. Lacustrine plains, plains that formed in a lacustrine environment, that is, as the bed of a lake. Lava plains, formed by sheets of flowing lava. Erosional plains have been leveled by various agents of denudation such as running water, rivers and glacier which wear out the rugged surface and smoothens them. Plain resulting from the action of these agents of denudation are called peneplains while plains formed from wind action are called pediplains.
Structural plains are undisturbed horizontal surfaces of the Earth. They are structurally depressed areas of the world that make up some of the most extensive natural lowlands on the Earth's surface. Altiplano Altiplano Cundiboyacense Caroni Plain Chilean Central Valley Gran Chaco Los Llanos Venezuelan Llanos Argentine Pampas Atlantic coastal plain Carrizo Plain Great Plains Gulf Coastal Plain Interior Plains Lake Superior Lowland Laramie Plains Mississippi Alluvial Plain Oxnard Plain Snake River Plain Chianan Plain Depsang Plains Kantō Plain Kedu Plain Kewu Plain Mallig Plains Nōbi Plain North China Plain Osaka Plain Pingtung Plain Sarobetsu plain West Siberian Plain Yilan Plain Bhuikhel Depsang Plains Dooars Eastern coastal plains Indo-Gangetic Plains More plains North Bengal plains Punjab Plains Terai Utkal Plains Western coastal plains Al-Ghab Plain Aleppo plateau Ararat plain Israeli coastal plain Khuzestan Plain Mugan plain Nineveh Plains Shiraki Plain Limagne North German Plain Ochsenfeld Pannonian Basin Parndorf Plain Westphalian Lowland Bărăgan Plain Danubian Plain Dnieper Lowland East European Plain European Plain Great Hungarian Plain Kosovo field Little Hungarian Plain Pannonian Steppe Polesian Lowland Upper Thracian Plain Wallachian Plain Cheshire Plain Hardangervidda Kaffiøyra Muddus plains North
Mean sea level is an average level of the surface of one or more of Earth's oceans from which heights such as elevation may be measured. MSL is a type of vertical datum – a standardised geodetic datum –, used, for example, as a chart datum in cartography and marine navigation, or, in aviation, as the standard sea level at which atmospheric pressure is measured to calibrate altitude and aircraft flight levels. A common and straightforward mean sea-level standard is the midpoint between a mean low and mean high tide at a particular location. Sea levels can be affected by many factors and are known to have varied over geological time scales; however 20th century and current millennium sea level rise is caused by global warming, careful measurement of variations in MSL can offer insights into ongoing climate change. The term above sea level refers to above mean sea level. Precise determination of a "mean sea level" is difficult to achieve because of the many factors that affect sea level. Instantaneous sea level varies quite a lot on several scales of space.
This is because the sea is in constant motion, affected by the tides, atmospheric pressure, local gravitational differences, salinity and so forth. The easiest way this may be calculated is by selecting a location and calculating the mean sea level at that point and use it as a datum. For example, a period of 19 years of hourly level observations may be averaged and used to determine the mean sea level at some measurement point. Still-water level or still-water sea level is the level of the sea with motions such as wind waves averaged out. MSL implies the SWL further averaged over a period of time such that changes due to, e.g. the tides have zero mean. Global MSL refers to a spatial average over the entire ocean. One measures the values of MSL in respect to the land. In the UK, the Ordnance Datum is the mean sea level measured at Newlyn in Cornwall between 1915 and 1921. Prior to 1921, the vertical datum was MSL at the Victoria Liverpool. Since the times of the Russian Empire, in Russia and other former its parts, now independent states, the sea level is measured from the zero level of Kronstadt Sea-Gauge.
In Hong Kong, "mPD" is a surveying term meaning "metres above Principal Datum" and refers to height of 1.230m below the average sea level. In France, the Marégraphe in Marseilles measures continuously the sea level since 1883 and offers the longest collapsed data about the sea level, it is used for main part of Africa as official sea level. As for Spain, the reference to measure heights below or above sea level is placed in Alicante. Elsewhere in Europe vertical elevation references are made to the Amsterdam Peil elevation, which dates back to the 1690s. Satellite altimeters have been making precise measurements of sea level since the launch of TOPEX/Poseidon in 1992. A joint mission of NASA and CNES, TOPEX/Poseidon was followed by Jason-1 in 2001 and the Ocean Surface Topography Mission on the Jason-2 satellite in 2008. Height above mean sea level is the elevation or altitude of an object, relative to the average sea level datum, it is used in aviation, where some heights are recorded and reported with respect to mean sea level, in the atmospheric sciences, land surveying.
An alternative is to base height measurements on an ellipsoid of the entire Earth, what systems such as GPS do. In aviation, the ellipsoid known as World Geodetic System 84 is used to define heights; the alternative is to use a geoid-based vertical datum such as NAVD88. When referring to geographic features such as mountains on a topographic map, variations in elevation are shown by contour lines; the elevation of a mountain denotes the highest point or summit and is illustrated as a small circle on a topographic map with the AMSL height shown in metres, feet or both. In the rare case that a location is below sea level, the elevation AMSL is negative. For one such case, see Amsterdam Airport Schiphol. To extend this definition far from the sea means comparing the local height of the mean sea surface with a "level" reference surface, or geodetic datum, called the geoid. In a state of rest or absence of external forces, the mean sea level would coincide with this geoid surface, being an equipotential surface of the Earth's gravitational field.
In reality, due to currents, air pressure variations and salinity variations, etc. this does not occur, not as a long-term average. The location-dependent, but persistent in time, separation between mean sea level and the geoid is referred to as ocean surface topography, it varies globally in a range of ± 2 m. Adjustments were made to sea-level measurements to take into account the effects of the 235 lunar month Metonic cycle and the 223-month eclipse cycle on the tides. Several terms are used to describe the changing relationships between sea level and dry land; when the term "relative" is used, it means change relative to a fixed point in the sediment pile. The term "eustatic" refers to global changes in sea level relative to a fixed point, such as the centre of the earth, for example as a result of melting ice-caps; the term "steric" refers to global changes in sea level due to thermal expansion and salinity variations. The term "isostatic" refers to changes in
A stream is a body of water with surface water flowing within the bed and banks of a channel. The stream encompasses surface and groundwater fluxes that respond to geological, geomorphological and biotic controls. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long large streams are called rivers. Streams are important as conduits in the water cycle, instruments in groundwater recharge, corridors for fish and wildlife migration; the biological habitat in the immediate vicinity of a stream is called a riparian zone. Given the status of the ongoing Holocene extinction, streams play an important corridor role in connecting fragmented habitats and thus in conserving biodiversity; the study of streams and waterways in general is known as surface hydrology and is a core element of environmental geography. Brook A stream smaller than a creek one, fed by a spring or seep, it is small and forded. A brook is characterised by its shallowness.
Creek In North America and New Zealand, a small to medium-sized natural stream. Sometimes navigable by motor craft and may be intermittent. In parts of Maryland, New England, the UK and India, a tidal inlet in a salt marsh or mangrove swamp, or between enclosed and drained former salt marshes or swamps. In these cases, the stream is the tidal stream, the course of the seawater through the creek channel at low and high tide. River A large natural stream, which may be a waterway. Runnel the linear channel between the parallel ridges or bars on a shoreline beach or river floodplain, or between a bar and the shore. Called a swale. Tributary A contributory stream, or a stream which does not reach a static body of water such as a lake or ocean, but joins another river. Sometimes called a branch or fork. There are a number of regional names for a stream. Allt is used in Highland Scotland. Beck is used in Lincolnshire to Cumbria in areas which were once occupied by the Danes and Norwegians. Bourne or winterbourne is used in the chalk downland of southern England.
Brook. Burn is used in North East England. Gill or ghyll is seen in Surrey influenced by Old Norse; the variant "ghyll" is used in the Lake District and appears to have been an invention of William Wordsworth. Nant is used in Wales. Rivulet is a term encountered in Victorian era publications. Stream Syke is used in lowland Cumbria for a seasonal stream. Branch is used to name streams in Virginia. Creek is common throughout the United States, as well as Australia. Falls is used to name streams in Maryland, for streams/rivers which have waterfalls on them if such falls have a small vertical drop. Little Gunpowder Falls and The Jones Falls are rivers named in this manner, unique to Maryland. Kill in New York, Pennsylvania and New Jersey comes from a Dutch language word meaning "riverbed" or "water channel", can be used for the UK meaning of'creek'. Run in Ohio, Michigan, New Jersey, Virginia, or West Virginia can be the name of a stream. Run in Florida is the name given to streams coming out of small natural springs.
River is used for larger springs like the Silver Rainbow River. Stream and brook are used in Midwestern states, Mid-Atlantic states, New England. Bar A shoal that develops in a stream as sediment is deposited as the current slows or is impeded by wave action at the confluence. Bifurcation A fork into two or more streams. Channel A depression created by constant erosion. Confluence The point at which the two streams merge. If the two tributaries are of equal size, the confluence may be called a fork. Drainage basin The area of land. A large drainage basin such as the Amazon River contains many smaller drainage basins. Floodplain Lands adjacent to the stream that are subject to flooding when a stream overflows its banks. Gaging station A site along the route of a stream or river, used for reference marking or water monitoring. Headwaters The part of a stream or river proximate to its source; the word is most used in the plural where there is no single point source. Knickpoint The point on a stream's profile where a sudden change in stream gradient occurs.
Mouth The point at which the stream discharges via an estuary or delta, into a static body of water such as a lake or ocean. Pool A segment where the water is deeper and slower moving. Rapids A turbulent, fast-flowing stretch of a stream or river. Riffle A segment where the flow is shallower and more turbulent. River A large natural stream, which may be a waterway. Run A somewhat smoothly flowing segment of the stream. Source The spring, or other point of origin of a stream. Spring The point at which a stream emerges from an underground course through unconsolidated sediments or through caves. A stream can with caves, flow aboveground for part of its course, underground for part of its course. Stream bed The bottom of a stream. Stream corridor Stream, its floodplains, the transitional upland fringe Streamflow The water moving through a stream channel. Thalweg The river's longitudinal section, or the line joining the deepest point in the channel at each stage from source to mouth. Waterfall or cascade The fall of water where the stream goes over a sudden drop called a knickpoint.
The stream expends kinetic energy in "trying" to eliminate the
A riffle is a shallow landform in a flowing channel, it has specific topographic and hydraulic indicators. These are always assessed at a low discharge compared to the flow that fills the channel, as a result the water moving over a riffle appears shallow and fast, with a wavy, disturbed water surface; the water's surface over a riffle at low flow has a much steeper slope than that over other in-channel landforms. Channel sections with a mean water surface slope of 0.1 to 0.5% exhibit riffles, though they can occur in steeper or gentler sloping channels with coarser or finer bed materials, respectively. Except in the period after a flood, the sediment on the riverbed in a riffle is much coarser than on that in any other in-channel landform. Terrestrial valleys consist of channels – geometric depressions in the valley floor carved by flowing water – and overbank regions that include floodplains and terraces; some channels have sizes that hardly change along the river. However, many channels exhibit apparent changes in width, bed elevation, slope.
In these cases, scientists realized that the riverbed tends to rise and fall with distance downstream relative to an average elevation of the river's slope. That led scientists to map the bed elevation down the deepest path in a channel, called the thalweg, to obtain a longitudinal profile; the piecewise linear slope of the river is computed and removed to leave just the rise and fall of the elevation about the channel's trendline. According to the zero-crossing method, riffles are all the locations along the channel whose residual elevation is greater than zero; because of the prevalence of this method for identifying and mapping riffles, riffles are thought of as part of a paired sequence, alternating with pools- the lows between the riffles. However, modern topographic maps of rivers with meter-scale resolution reveal that rivers exhibit a diversity of in-channel landforms. For a long time, scientists have observed that, all other things being equal, riffles tend to be wider than other in-channel landforms, but only has there been high enough quality of river maps to confirm that this is true.
The physics mechanism that explains why this happens is called flow convergence routing. This mechanism may be used in river engineering to design self-sustainable riffles, given a suitable sediment supply and flow regime; when an in-channel landform is shallow and narrow, instead of shallow and wide, it is called a nozzle. Riffles are biologically important, because many aquatic species rely on them in one way or another. Many benthic macroinvertebrates are present in riffles, so fish locate just downstream of a riffle to wait for these small creatures to drift down to them; that draws fisherman to these natural fish feeding stations as well. Riffles serve to aerate the water, increasing the amount of dissolved oxygen. In the fishkeeping world, a "riffle tank" is one specializing in aquatic life that originates in places with powerful currents like riffles; these are emulated with powerful pumps. The term is applied to strips of wood, metal or plastic laid across the washing tables during gravity separation of gold in alluvial or placer mining.
The American Bottom is the flood plain of the Mississippi River in the Metro-East region of Southern Illinois, extending from Alton, south to the Kaskaskia River. It is sometimes called "American Bottoms"; the area is about 175 square miles protected from flooding in the 21st century by a levee and drainage canal system. Across the river from St. Louis, Missouri are industrial and urban areas, but many swamps and the major Horseshoe Lake are reminders of the Bottoms' riparian nature; this plain served as the center for the pre-Columbian Cahokia Mounds civilization, the French settlement of Illinois Country. Deforestation of the river banks in the 19th century to fuel steamboats had dramatic environmental effects in this region; the Mississippi River between St. Louis and the confluence with the Ohio River became wider and more shallow, as unstable banks collapsed into the water; this resulted in more severe flooding and lateral changes of the major channel, causing the destruction of several French colonial towns, such as Kaskaskia, which relocated.
The southern portion of the American Bottoms is agricultural, planted chiefly in corn and soybean. The American Bottom is part of the Mississippi Flyway used by migrating birds and has the greatest concentration of bird species in Illinois; the flood plain is bounded on the east by a nearly continuous, 200- to 300-foot high, 80-mile long bluff of limestone and dolomite, above which begins the great prairie that covers most of the state. The Mississippi River bounds the Bottom on its west, the river abuts the bluffline on the Missouri side. Portions of St. Clair, Madison and Randolph counties are in the American Bottom, its maximum width is about 9 miles in the north, it is about 2 to 3 miles in width throughout most of its southern extent. Before European settlement, the area was home to indigenous peoples for many centuries; the peak civilization was created by peoples of the Mississippian culture, known as the Mound Builders. With the cultivation of maize, they were able to create food surpluses and build concentrated settlements in the centuries after 600 CE.
The Cahokia Mounds Site, built as the center attracted a rapid increase in population after 1000 CE, is a six-square mile complex of large, man-made, earthen mounds rising from the flood plain. In 1982, it was designated by UNESCO as one of only eight World Heritage Sites in the United States; the most prominent structure is Monks Mound, rising ten stories high at the center of the complex and fronting on a 40-acre Grand Plaza. Monks Mound is the largest Pre-Columbian earthwork in the Americas, the complex is the largest earthwork north of Mexico; the engineering of the mounds showed that their builders had an expert knowledge of the varying soils and their capacities. Cahokia was a complex and designed urban center with a residential population and artisan production of refined crafts and goods. With its location at the confluence of three major rivers, it was the center of a regional trading network reaching to the Great Lakes and the Gulf Coast. With a population estimated at 30,000 at its peak, Cahokia was the largest city north of modern-day Mexico.
For ecological reasons—deforestation and overhunting—the city went into decline after 1300 and was abandoned before 1400. No city in the territorial United States surpassed this population until after 1800, when Philadelphia exceeded it. Archaeological investigation has determined that the various types of mounds were arranged in a planned construction that reflected the cosmology of the Mississippians; the smaller ridge-top and conical mounds were used for ritual burials, some for elites and some for apparent sacrifices. The larger platform mounds were used for homes of the elite. Archaeologists have found remains of a 2-mile long, defensive wooden stockade that enclosed the central precinct and was rebuilt several times, they discovered two major solar calendars, now known as Woodhenge, as the works were constructed of cedar, considered a sacred wood. The area surrounding the mounds had numerous borrow pits from which soil was taken to build the mounds and to fill and level the Grand Plaza and other plazas.
After Cahokia was abandoned, there were few indigenous inhabitants in the area in the 17th century at the time of first French exploration. The French made the earliest European settlement in this region of the Mississippi River Valley, they encountered Illiniwek clans called Cahokia, after whom they named the earthwork complex, Kaskaskia, after whom the French named a river and town. The French villages included Kaskaskia, Prairie du Rocher, St. Philippe, Prairie du Pont. Examples of 18th-century French Colonial architecture survive here, including the old Cahokia courthouse and Holy Family Catholic Church, both made with the distinctive vertical-log construction known as poteaux-sur-solle. American settlers began arriving near the end of the American Revolution after the Illinois Country was ceded by Great Britain to the new United States. In the early years, American single men came to the country, there was little government and much anarchy; as Americans arrived, many residents of French descent moved west of the Mississippi River to St. Louis and Ste.
Genevieve, Missouri. Within several years, the former French colonial towns had become American in population, English dominated as the language; the Goshen Settlement was an early American settlement at the edge of the Bottom. The settlers continued to use the rich alluvial floodplain for agriculture until the late 19th century. Brooklyn, Illinois was founded by 1839 as a freedom villa