An alligator is a crocodilian in the genus Alligator of the family Alligatoridae. The two living species are the Chinese alligator. Additionally, several extinct species of alligator are known from fossil remains. Alligators first appeared during the Oligocene epoch about 37 million years ago; the name "alligator" is an anglicized form of el lagarto, the Spanish term for "the lizard", which early Spanish explorers and settlers in Florida called the alligator. English spellings of the name included allagarta and alagarto. An average adult American alligator's weight and length is 360 kg and 4 m, but they sometimes grow to 4.4 m long and weigh over 450 kg. The largest recorded, found in Louisiana, measured 5.84 m. The Chinese alligator is smaller exceeding 2.1 m in length. Additionally, it weighs less, with males over 45 kg. Adult alligators are black or dark olive-brown with white undersides, while juveniles have contrasting white or yellow marks which fade with age. No average lifespan for an alligator has been measured.
In 1937, an adult specimen was brought to the Belgrade Zoo in Serbia from Germany. It is now at least 80 years old. Although no valid records exist about its date of birth, this alligator named Muja, is considered the oldest alligator living in captivity. †Alligator mcgrewi †Alligator mefferdi †Alligator olseni †Alligator prenasalis Alligators are native to only the United States and China. American alligators are found in the southeast United States: all of Louisiana. According to the 2005 Scholastic Book of World Records, Louisiana has the largest alligator population; the majority of American alligators inhabit Florida and Louisiana, with over a million alligators in each state. Southern Florida is the only place where both crocodiles live side by side. American alligators live in freshwater environments, such as ponds, wetlands, rivers and swamps, as well as in brackish water; when they construct alligator holes in the wetlands, they increase plant diversity and provide habitat for other animals during droughts.
They are, considered an important species for maintaining ecological diversity in wetlands. Farther west, in Louisiana, heavy grazing by coypu and muskrat are causing severe damage to coastal wetlands. Large alligators feed extensively on coypu, provide a vital ecological service by reducing coypu numbers; the Chinese alligator is found in only the Yangtze River valley and parts of adjacent provinces and is endangered, with only a few dozen believed to be left in the wild. Indeed, far more Chinese alligators live in zoos around the world. Rockefeller Wildlife Refuge in southern Louisiana has several in captivity in an attempt to preserve the species. Miami MetroZoo in Florida has a breeding pair of Chinese alligators. Large male alligators are solitary territorial animals. Smaller alligators can be found in large numbers close to each other; the largest of the species defend prime territory. Alligators move on land by two forms of locomotion referred to as "sprawl" and "high walk"; the sprawl is a forward movement with the belly making contact with the ground and is used to transition to "high walk" or to slither over wet substrate into water.
The high walk is an up on four limbs forward motion used for overland travel with the belly well up from the ground. Alligators have been observed to rise up and balance on their hind legs and semi-step forward as part of a forward or upward lunge; however they can not walk on their hind legs for long distances. Although the alligator has a heavy body and a slow metabolism, it is capable of short bursts of speed in short lunges. Alligators' main prey are smaller animals they can eat with a single bite, they may kill larger prey by dragging it into the water to drown. Alligators consume food that cannot be eaten in one bite by allowing it to rot, or by biting and spinning or convulsing wildly until bite-sized chunks are torn off; this is referred to as a "death roll". Critical to the alligator's ability to initiate a death roll, the tail must flex to a significant angle relative to its body. An alligator with an immobilized tail cannot perform a death roll. Most of the muscle in an alligator's jaw evolved to grip prey.
The muscles that close the jaws are exceptionally powerful, but the muscles for opening their jaws are comparatively weak. As a result, an adult human can hold an alligator's jaws shut bare-handed, it is common today to use several wraps of duct tape to prevent an adult alligator from opening its jaws when being handled or transported. Alligators are timid towards humans and tend to walk or swim away if one approaches; this has led some people to the practice of approaching alligators and their nests in a manner that may provoke the animals into attacking. In Florida, feeding wild alligators at any time is illegal. If fed, the alligators will lose their fear of humans and will learn to associate humans with food, thereby becoming both a greater danger to people, at greater risk from them; the type of food eaten by alligators depends upon their size. When young, alligators eat fish, snails and worms; as they mature, progressively larger prey is taken, including larger fish such as gar and various
Acer is a genus of trees and shrubs known as maple. The genus is placed in the family Sapindaceae. There are 128 species, most of which are native to Asia, with a number appearing in Europe, northern Africa, North America. Only one species, Acer laurinum, extends to the Southern Hemisphere; the type species of the genus is the sycamore maple, Acer pseudoplatanus, the most common maple species in Europe. The maples have recognizable palmate leaves and distinctive winged fruits; the closest relatives of the maples are the horse chestnuts. Most maples are trees growing to a height of 10–45 m. Others are shrubs less than 10 meters tall with a number of small trunks originating at ground level. Most species are deciduous, many are renowned for their autumn leaf colour, but a few in southern Asia and the Mediterranean region are evergreen. Most are shade-tolerant when young and are riparian, understory, or pioneer species rather than climax overstory trees. There are a few exceptions such as sugar maple.
Many of the root systems are dense and fibrous, inhibiting the growth of other vegetation underneath them. A few species, notably Acer cappadocicum produce root sprouts, which can develop into clonal colonies. Maples are distinguished by opposite leaf arrangement; the leaves in most species are palmate veined and lobed, with 3 to 9 veins each leading to a lobe, one of, central or apical. A small number of species differ in having palmate compound, pinnate compound, pinnate veined or unlobed leaves. Several species, including Acer griseum, Acer mandshuricum, Acer maximowiczianum and Acer triflorum, have trifoliate leaves. One species, Acer negundo, has pinnately compound leaves that may be trifoliate or may have five, seven, or nine leaflets. A few, such as Acer laevigatum and Acer carpinifolium, have pinnately veined simple leaves. Maple species, such as Acer rubrum, may be dioecious or polygamodioecious; the flowers are regular and borne in racemes, corymbs, or umbels. They have four or five sepals, four or five petals about 1 – 6 mm long, four to ten stamens about 6 – 10 mm long, two pistils or a pistil with two styles.
The ovary is superior and has two carpels, whose wings elongate the flowers, making it easy to tell which flowers are female. Maples flower in late winter or early spring, in most species with or just after the appearance of the leaves, but in some before the trees leaf out. Maple flowers are green, orange or red. Though individually small, the effect of an entire tree in flower can be striking in several species; some maples are an early spring source of nectar for bees. The distinctive fruits are called samaras, "maple keys", "helicopters", "whirlybirds" or "polynoses"; these seeds occur in distinctive pairs each containing one seed enclosed in a "nutlet" attached to a flattened wing of fibrous, papery tissue. They are shaped to carry the seeds a considerable distance on the wind. People call them "helicopters" due to the way that they spin as they fall. During World War II, the US Army developed a special air drop supply carrier that could carry up to 65 pounds of supplies and was based on the Maple seed.
Seed maturation is in a few weeks to six months after flowering, with seed dispersal shortly after maturity. However, one tree can release hundreds of thousands of seeds at a time. Depending on the species, the seeds can be green to orange and big with thicker seed pods; the green seeds are released in pairs, sometimes with the stems still connected. The yellow seeds are released individually and always without the stems. Most species require stratification in order to germinate, some seeds can remain dormant in the soil for several years before germinating; the genus Acer together with genus Dipteronia are either classified in a family of their own, the Aceraceae, or else classified as members of the family Sapindaceae. Recent classifications, including the Angiosperm Phylogeny Group system, favour inclusion in Sapindaceae; when put in family Sapindaceae, genus Acer is put in subfamily Hippocastanoideae. The genus is subdivided by its morphology into a multitude of subsections. Fifty-four species of maples meet the International Union for Conservation of Nature criteria for being under threat of extinction in their native habitat.
The leaves are used as a food plant for the larvae of a number of the Lepidoptera order.. In high concentrations, like the greenstriped mapleworm, can feed on the leaves so much that they cause temporary defoliation of host maple trees. Aphids are very common sap-feeders on maples. In horticultural applications a dimethoate spray will solve this. In the United States and Canada, all maple species are threatened by the Asian long-horned beetle. Infestations have resulted in the destruction of thousands of maples and other tree species in Illinois, New Jersey and New York. Maples are affected by a number of fungal diseases. Several are susceptible to Verticillium wilt caused by Verticillium species, which can cause significant local mortality. Sooty bark disease, caused by Cryptostroma species, can kill trees that are under stress due to drought. Death of maples can be caused by Phytophthora root rot and Ganoderma root decay. Maple leaves in late summer and autumn are disfigured by "tar spot" caused by Rhytisma species and mildew caused by Uncinula species, though these diseases do not have an adverse effect on th
Coles Creek culture
Coles Creek culture is a Late Woodland archaeological culture in the Lower Mississippi valley in the southern United States. It followed the Troyville culture; the period marks a significant change in the cultural history of the area. Population increased and there is strong evidence of a growing cultural and political complexity by the end of the Coles Creek sequence. Although many of the classic traits of chiefdom societies are not yet manifested, by 1000 CE the formation of simple elite polities had begun. Coles Creek sites are found in Arkansas and Mississippi, it is considered ancestral to the Plaquemine culture. The Coles Creek culture is an indigenous development of the Lower Mississippi Valley that took place between the terminal Woodland period and the Plaquemine culture period; the period is marked by the increased use of flat-topped platform mounds arranged around central plazas, more complex political institutions, a subsistence strategy still grounded in the Eastern Agricultural Complex and hunting rather than on the maize plant as would happen in the succeeding Plaquemine Mississippian period.
The culture was defined by the unique decoration on grog-tempered ceramic ware by James A. Ford after his investigations at the Mazique Archeological Site, he had studied both the Mazique and Coles Creek Sites, went with the Mazique culture, but decided on the less involved sites name. The Coles Creak area is further subdivided into Coles Creek proper in the northern part of its range throughout the interior Mississippi Valley, Coastal Coles Creek, being found along the Gulf coast south of the latitude of modern Baton Rouge, Louisiana. Although earlier cultures built mounds as a part of mortuary customs, by the Coles Creek period these mounds took on a newer shape and function. Instead of being for burial, mounds were constructed to support temples and other civic structures. Pyramidal mounds with flat tops and ramps were constructed over successive years and with many layers. A temple or other structures of wattle and daub construction, would be built on the summit of the mound. A typical Coles Creek site plan consisted of at least two, more three, mounds around a central plaza.
This pattern emerged in 800 CE and continued for several hundred years. By late Coles Creek times, the site plans are enlarged to include up to three more mounds. Sites typical of this period are Mount Nebo, Holly Bluff, Kings Crossing, Lake Agnes. Many Coles Creek mounds were erected over earlier mortuary mounds, leading researchers to speculate that emerging elites were symbolically and physically appropriating dead ancestors to emphasize and project their own authority. Long-distance trade seems to have been negligible at this time, as exotic goods and trade items are rare in Coles Creek sites. There is little evidence of domesticated or cultivated plants until the end of the Coles Creek period. Acorns are a dominant food source, supplemented with persimmons and some starchy seeds such as maygrass. Coles Creek populations may have loosely "managed" certain plant resources in order to promote a better or more consistent food supply. Maize is found in limited quantities, but by 1000-1200 CE had begun to increase, although nowhere near the levels it would reach in Mississippian culture times.
The bow and arrow was introduced in this period. Pottery styles changed during this period, as people began to create more durable wares with more diversified uses. Wet clay was tempered with particles of dry clay to prevent cracking during firing. Most pots were decorated only on the upper half with designs of incised lines or impressed tool marks. Colors ranged from tan, black and gray, although the rare red example is known; the rare effigy pot is found. Plum Bayou culture Culture and chronological table for the Mississippi Valley Hudson, Charles M. Knights of Spain, Warriors of the Sun: Hernando De Soto and the South's Ancient Chiefdoms, University of Georgia Press, 1997. ISBN 0-8203-1888-4 R. Barry Lewis and Charles Stout, editors. "Mississippian Towns and Sacred Spaces", University of Alabama Press, 1998. ISBN 0-8173-0947-0 Southeastern Prehistory - Late Woodland Period
The Mississippian culture was a mound-building Native American civilization archeologists date from about 800 CE to 1600 CE, varying regionally. It was composed of a series of urban settlements and satellite villages linked together by a loose trading network; the largest city was Cahokia, believed to be a major religious center. The civilization flourished from the southern shores of the Great Lakes at Western New York and Western Pennsylvania in what is now the Eastern Midwest, extending south-southwest into the lower Mississippi Valley and wrapping easterly around the southern foot of the Appalachians barrier range into what is now the Southeastern United States; the Mississippian way of life began to develop in the Mississippi River Valley. Cultures in the tributary Tennessee River Valley may have begun to develop Mississippian characteristics at this point. All dated Mississippian sites predate 1539–1540, with notable exceptions being Natchez communities that maintained Mississippian cultural practices into the 18th century.
A number of cultural traits are recognized as being characteristic of the Mississippians. Although not all Mississippian peoples practiced all of the following activities, they were distinct from their ancestors in adoption of some or all of these traits; the construction of large, truncated earthwork pyramid mounds, or platform mounds. Such mounds were square, rectangular, or circular. Structures were constructed atop such mounds. Maize-based agriculture. In most places, the development of Mississippian culture coincided with adoption of comparatively large-scale, intensive maize agriculture, which supported larger populations and craft specialization. Women ate more maize, whereas men ate more animal meat. Shell-tempered pottery; the adoption and use of riverine shells as tempering agents in ceramics. Widespread trade networks extending as far west as the Rockies, north to the Great Lakes, south to the Gulf of Mexico, east to the Atlantic Ocean; the development of the chiefdom or complex chiefdom level of social complexity.
The development of institutionalized social inequality. A centralization of control of combined political and religious power in the hands of few or one; the beginnings of a settlement hierarchy, in which one major center has clear influence or control over a number of lesser communities, which may or may not possess a smaller number of mounds. The adoption of the paraphernalia of the Southeastern Ceremonial Complex called the Southern Cult; this is the belief system of the Mississippians. SECC items are found in Mississippian-culture sites from Wisconsin to the Gulf Coast, from Florida to Arkansas and Oklahoma; the SECC was tied into ritual game-playing, as with chunkey. The Mississippians had no writing stone architecture, they worked occurring metal deposits, such as hammering and annealing copper for ritual objects such as Mississippian copper plates and other decorations, but did not smelt iron or practice bronze metallurgy. The Mississippi stage is divided into three or more chronological periods.
Each period is an arbitrary historical distinction varying regionally. At a particular site, each period may be considered to begin earlier or depending on the speed of adoption or development of given Mississippian traits; the "Mississippi period" should not be confused with the "Mississippian culture". The Mississippi period is the chronological stage, while Mississippian culture refers to the cultural similarities that characterize this society; the Early Mississippi period had just transitioned from the Late Woodland period way of life. Different groups abandoned tribal lifeways for increasing complexity, sedentism and agriculture. Production of surplus corn and attractions of the regional chiefdoms led to rapid population concentrations in major centers; the Middle Mississippi period is the apex of the Mississippi era. The expansion of the great metropolis and ceremonial complex at Cahokia, the formation of other complex chiefdoms, the spread and development of SECC art and symbolism are characteristic changes of this period.
The Mississippian traits listed above came to be widespread throughout the region. The Late Mississippi period is characterized by increasing warfare, political turmoil, population movement; the population of Cahokia dispersed early in this period migrating to other rising political centers. More defensive structures are seen at sites, sometimes a decline in mound-building and large-scale, public ceremonialism. Although some areas continued an Middle Mississippian culture until the first significant contact with Europeans, the population of most areas had dispersed or were experiencing severe social stress by 1500. Along with the contemporaneous Ancestral Pueblo peoples, these cultural collapses coincide with the global climate change of the Little Ice Age. Scholars theorize drought and the reduction of maize agriculture, together with possible deforestation and overhunting by the concentrated populations, forced them to move away from major sites; this period ended with European contact in the 16th century.
The term Middle Mississippian is used to describe the core of the classic Mississippian culture area. This area covers the central Mississippi River Valley, the lower Ohio River Valley, most of the Mid-South area, including western and central Kentucky, western Tennessee, northern Alabama and Mississippi. Sites in this area often
Chert is a hard, fine-grained sedimentary rock composed of crystals of quartz that are small. Quartz is the mineral form of silicon dioxide. Chert is of biological origin but may occur inorganically as a chemical precipitate or a diagenetic replacement. Geologists use chert as a generic name for any type of cryptocrystalline quartz. Chert is of biological origin, being the petrified remains of siliceous ooze, the biogenic sediment that covers large areas of the deep ocean floor, which contains the silicon skeletal remains of diatoms, silicoflagellates, radiolarians. Depending on its origin, it can contain small macrofossils, or both, it varies in color, but most manifests as gray, grayish brown and light green to rusty red. Chert occurs in carbonate rocks as oval to irregular nodules in greensand, limestone and dolostone formations as a replacement mineral, where it is formed as a result of some type of diagenesis. Where it occurs in chalk or marl, it is called flint, it occurs in thin beds, when it is a primary deposit.
Thick beds of chert occur in deep marine deposits. These thickly bedded cherts include the novaculite of the Ouachita Mountains of Arkansas and similar occurrences in Texas and South Carolina in the United States; the banded iron formations of Precambrian age are composed of alternating layers of chert and iron oxides. Chert occurs in diatomaceous deposits and is known as diatomaceous chert. Diatomaceous chert consists of beds and lenses of diatomite which were converted during diagenesis into dense, hard chert. Beds of marine diatomaceous chert comprising strata several hundred meters thick have been reported from sedimentary sequences such as the Miocene Monterey Formation of California and occur in rocks as old as the Cretaceous. In petrology the term "chert" is used to refer to all rocks composed of microcrystalline, cryptocrystalline and microfibrous quartz; the term does not include quartzite. Chalcedony is a microfibrous variety of quartz. Speaking, the term "flint" is reserved for varieties of chert which occur in chalk and marly limestone formations.
Among non-geologists, the distinction between "flint" and "chert" is one of quality – chert being lower quality than flint. This usage of the terminology is prevalent in North America and is caused by early immigrants who brought the terms from England where most true flint was indeed of better quality than "common chert". Among petrologists, chalcedony is sometimes considered separately from chert due to its fibrous structure. Since many cherts contain both microcrystalline and microfibrous quartz, it is sometimes difficult to classify a rock as chalcedony, thus its general inclusion as a variety of chert; the cryptocrystalline nature of chert, combined with its above average ability to resist weathering, recrystallization and metamorphism has made it an ideal rock for preservation of early life forms. For example: The 3.2 Ga chert of the Fig Tree Formation in the Barbeton Mountains between Swaziland and South Africa preserved non-colonial unicellular bacteria-like fossils. The Gunflint Chert of western Ontario preserves not only bacteria and cyanobacteria but organisms believed to be ammonia-consuming and some that resemble green algae and fungus-like organisms.
The Apex Chert of the Pilbara craton, Australia preserved eleven taxa of prokaryotes. The Bitter Springs Formation of the Amadeus Basin, Central Australia, preserves 850 Ma cyanobacteria and algae; the Rhynie chert of Scotland has remains of a Devonian land flora and fauna with preservation so perfect that it allows cellular studies of the fossils. In prehistoric times, chert was used as a raw material for the construction of stone tools. Like obsidian, as well as some rhyolites, felsites and other tool stones used in lithic reduction, chert fractures in a Hertzian cone when struck with sufficient force; this results in a characteristic of all minerals with no cleavage planes. In this kind of fracture, a cone of force propagates through the material from the point of impact removing a full or partial cone; the partial Hertzian cones produced during lithic reduction are called flakes, exhibit features characteristic of this sort of breakage, including striking platforms, bulbs of force, eraillures, which are small secondary flakes detached from the flake's bulb of force.
When a chert stone is struck against an iron-bearing surface sparks result. This makes chert an excellent tool for starting fires, both flint and common chert were used in various types of fire-starting tools, such as tinderboxes, throughout history. A primary historic use of common chert and flint was for flintlock firearms, in which the chert striking a metal plate produces a spark that ignites a small reservoir containing black powder, discharging the firearm. Cherts are subject to problems. Weathered chert develops surface pop-outs when used in concrete that undergoes freezing and thawing because of the high porosity of weathered cher
Celtis occidentalis known as the common hackberry, is a large deciduous tree native to North America. It is known as the nettletree, beaverwood, northern hackberry, American hackberry, it is a moderately long-lived hardwood with a light-colored wood, yellowish gray to light brown with yellow streaks. The common hackberry is distinguished from elms and some other hackberries by its cork-like bark with wart-like protuberances; the leaves are distinctly coarse-textured. It produces small fruits that turn orange-red to dark purple in the autumn staying on the trees for several months; the common hackberry is confused with the sugarberry and is most distinguished by range and habitat. The common hackberry has wider leaves that are coarser above than the sugarberry; the common hackberry is 9 to 15 metres in height, with a slender trunk. In the best conditions in the southern Mississippi Valley area, it can grow to 40 metres, it has pendulous branches. It will grow on gravelly or rocky hillsides; the roots are fibrous and it grows rapidly.
In the western part of its range, trees may still grow up to 29 m. The maximum age attained by hackberry is between 150 and 200 years in ideal conditions; the bark is light brown or silvery gray, broken on the surface into thick appressed scales and sometimes roughened with excrescences. The remarkable bark pattern is more pronounced in younger trees, with the irregularly-spaced ridges resembling long geologic palisades of sedimentary rock formations when viewed edge-wise. Coins as large as USA quarters can be laid flat against the valleys, which may be as deep as an adult human finger; the branchlets are slender, their color transitions from light green to red brown and to dark red-brown. The winter buds are axillary, acute, somewhat flattened, one-fourth of an inch long, light brown; the bud scales enlarge with the growing shoot, the innermost become stipules. No terminal bud is formed; the leaves are alternately arranged on the branchlets, ovate to ovate-lanceolate slightly falcate, 5–12 cm long by 3–9 cm oblique at the base, with a pointed tip.
The margin is serrate, except at the base, entire. The leaf has the midrib and primary veins prominent; the leaves come out of the bud conduplicate with involute margins, pale yellow green, downy. In autumn they turn to a light yellow. Petioles slender grooved, hairy. Stipules varying in form, caducous; the flowers appear in May, soon after the leaves. They are polygamo-monœcious, meaning that there are three kinds: staminate, perfect, they are born on slender drooping pedicels. The calyx is light yellow green, five-lobed, divided nearly to the base. There is no corolla. There are five stamens; the pistil has a two-lobed style and one-celled superior ovary containing solitary ovules. The fruit is a fleshy, oblong drupe, 1⁄4 to 3⁄8 in long, tipped with the remnants of style, dark purple when ripe, it ripens in September and October. It remains on the branches during winter; the endocarp contains significant amounts of biogenic carbonate, nearly pure aragonite. The common hackberry is native to North America from southern Ontario and Quebec, through parts of New England, south to North Carolina-, west to northern Oklahoma, north to South Dakota.
Hackberry's range overlaps with the sugarberry, making it difficult to establish the exact range of either species in the South. Although there is little actual overlap, in the western part of its range the common hackberry is sometimes confused with the smaller netleaf hackberry, which has a similar bark. Hackberry grows in many different habitats, although it prefers bottomlands and soils high in limestone, its shade tolerance is dependent on conditions. In favorable conditions its seedlings will persist under a closed canopy, but in less favorable conditions it can be considered shade intolerant; the leaves are eaten by four gall-producing insects of the genus Pachypsylla, which do not cause serious damage to the tree. A number of insects and fungi cause rapid decay of dead roots of the tree; the small berries, are eaten by a number of birds and mammals. Most seeds are dispersed by animals, but some seeds are dispersed by water; the tree serves as a butterfly larval host the hackberry emperor.
Hackberry's wood is light yellow. It rots making the wood undesirable commercially, although it is used for fencing and cheap furniture. Specific gravity, 0.7287. Sombor in Serbia and Bratislava, the capital of Slovakia, are known for the extensive use of hackberry as a str