|Politica de confidentialitate|
| • CREDITUL IPOTECAR PENTRU INVESTITII IMOBILIARE (economie)|
• Comertul cu amanuntul (economie)
• IDENTIFICAREA CRIMINALISTICA (drept)
• Mecanismul motor, Biela, organe mobile proiect (diverse)
• O scrisoare pierduta (romana)
• O scrisoare pierduta (romana)
• Ion DRUTA (romana)
• COMPORTAMENT PROSOCIAL-COMPORTAMENT ANTISOCIAL (psihologie)
• COMPORTAMENT PROSOCIAL-COMPORTAMENT ANTISOCIAL (psihologie)
• Starea civila (geografie)
| • domnisoara hus|
• istoria unui galban
• comentariu liric
• praslea cel voinic si merele da aur
|The history of United States of America|
The territory now part of the United States has been inhabited for from 15,000 to 40,000 years, as attested by local evidence. The aboriginal peoples, ancestral to today's American Indians, left no firm monuments on the scale of contemporaneous cultures elsewhere, but both the pueblos of the Southwest and the great mounds of the Mississippi River valley antedate the arrival of the European colonial powers. The original 13 British colonies that became the United States of America in 1776 were just one of several attempts by European powers to build empires in North America. All seized land from the native Indians, who then were usually either assimilated or driven off by superior European weapons. The Spaniards reached Florida as early as 1513 and New Mexico in 1540. The French began their exploration of the Mississippi River valley in 1673. The Russians reached Alaska in 1741. x1o8oc
Of all the colonizers, the British were the most successful. In 1607 Jamestown became the first permanent British settlement in North America and the foundation of the Virginia colony. It was followed 13 years later by the Pilgrim settlement at Plymouth, which was soon dwarfed by the Puritan colony of Massachusetts Bay. Most of New England was settled by Puritans fleeing either the harassment of Charles I or the orthodoxy of Massachusetts Bay. Pennsylvania was given to the Quaker William Penn as payment for a debt, and Maryland, a grant to the Roman Catholic George Calvert, was the first colony to establish religious freedom. New York, New Jersey, and Delaware were taken from the Dutch by the British in 1664, a year after the Carolinas had been granted to eight British noblemen. The 13th colony was Georgia, founded by James Oglethorpe in 1732 as a refuge for debtors and convicts.
When the British successfully evicted the French from North America in 1763, they embarked on a number of policies that the colonials found increasingly onerous. Settlement was prohibited west of the Appalachians and measures were passed to raise revenue in the colonies. These revenue-raising measures and Britain's generally exploitive mercantilist economic policy irked the colonials, who began to band together to oppose and subvert the measures. Britain increased its military presenceto enforce compliance (a presence part of whose cost was exacted from the colonials), and fighting broke out in 1775. The Second Continental Congress, acting for the 13 colonies, declared independence on July 4, 1776, and created. Articles of Confederation to govern the new nation. Victory over the British came in 1783, and the resulting Treaty of Paris established U.S. boundaries, except for Spanish Florida, west to the Mississippi River.
As the United States moved west, the issue of slavery was intensifying strains between the rapidly industrializing North and the slave-based agricultural South. The South was determined to maintain the institution of black slavery against the federal government's efforts to curtail the latter's spread. Several compromises over the slavery issue held the Union together for more than a half-century, but the election as president in 1860 of Abraham Lincoln, whose Republican Party clearly advocated the prohibition of slavery in the Western territories, led South Carolina to secede, joined by 10 other Southern states by the next year.
Lincoln denied the Southern states' right to secede. The North's defeat of the South in the ensuing Civil War (1861-65) resulted in the preservation of the Union, the abolition of slavery, the establishment of citizenship for former slaves, and the institution of universal adult male suffrage. Lincoln's plans for magnanimity to the defeated South were cut short by his assassination, and Congress, completely dominated by northern Radical Republicans, embarked on its own, more punitive scheme of reconstruction. This system, which protected black civil rights in the South, came to an end with the withdrawal of federal (Northern) troops by 1877. Thereafter, Southern blacks were gradually disenfranchised and forcibly segregated within the larger society.
The post-Civil War United States was characterized by rapid industrialization, a continuing westward movement across the Great Plains, a massive influx of foreign immigrants, and the slow emergence of the United States into a position of world power. The westward movement fueled by the desire for land, led to a long series of evictions of Plains Indians from their lands onto less desirable reservations. Immigration from Europe exceeded 13,000,000 between 1900 and 1914 alone and provided labour for the North's burgeoning factories. When Cuba revolted against Spain in 1895, American sympathies and interests ultimately led to war with Spain (1898). Victory brought the United States its first overseas territories (the Philippines, Guam, Puerto Rico) and marked it as an emergent international power. The United States' rise to great-power status had its price. Though President Woodrow Wilson pledged neutrality in World War I, the United States was unable to remain outside the struggle. Its entry into the war in 1917 was decisive in bringing about an Allied victory and commenced American involvement in the European balance of power.
The prosperity of the decade that followed World War I came to a sudden end
in 1929 when the stock market crashed and the Great Depression began. It ushered
in an era of increased federal involvement in economic and social policy under
President Franklin D. Roosevelt. His New Deal legislation revolutionized the
country, but full economic recovery was still not achieved until war production
became massive on the eve of World War II. The Japanese attack on Pearl Harbor
brought the United States into World War II on the side of Britain and the Soviet
Union against the fascist nations of Germany, Japan, and Italy. The war effort
galvanized the American economy's productive capacity, and after victory was
achieved in 1945 the United States experienced three decades of unprecedented
economic growth and prosperity.
Immense gorge cut by the Colorado River into the high plateaus of northwestern
Arizona, U.S., noted for its fantastic shapes and coloration.
Although its awesome grandeur and beauty are the major attractions of the Grand
Canyon, perhaps its most vital and valuable aspect lies in the time scale of
Earth history that is revealed in the exposed rocks of the canyon walls. No
other place on Earth compares with the Grand Canyon for its extensive and profound
record of geologic events. The canyon's record, however, is far from continuous
and complete. There are immense time gaps; many millions of years are unaccounted
for by gaps in the strata in which either vast quantities of Earth materials
were removed by erosion or there was little or no deposition of Earth materials.
Thus rock formations of vastly different ages are separated only by a thin,
distinct surface that reveals the vast unconformity in time.
The most significant aspect of the environment that is responsible for the canyon is frequently overlooked or not recognized. Were it not for the arid climate in the surrounding area, there would be no Grand Canyon. Slope wash from rainfall would have removed the canyon walls, the stairstep topography would long ago have been excavated, the distinctive sculpturing and the multicoloured rock structures could not exist, the Painted Desert would be gone, and the picturesque Monument Valley would have only a few rounded hillocks.
Biological past and present
Plant and animal fossils are not abundant in the Grand Canyon's sedimentary
rocks and are confined mostly to primitive algae and mollusks, corals, trilobites,
and other invertebrates. Animal life in the Grand Canyon area today is varied
and abundant, however. The common animals are the many varieties of squirrels,
coyotes, foxes, deer, badgers, bobcats, rabbits, chipmunks, and kangaroo rats.
Plant life is also varied. In the bottom of the canyons are willows and cottonwoods,
which require abundant water during the growing season. At the other end of
the moisture scale are drought-resistant plants such as the yucca, agave, and
numerous species of cactus.
Grand Canyon Series
Major division of rocks in northern Arizona dating from Precambrian time (about 3.8 billion to 540 million years ago). The rocks of the Grand Canyon Series consist of about 3,400 m (about 10,600 feet) of quartz sandstones, shales, and thick sequences of carbonate rocks. Spectacular exposures of these rocks occur in the Grand Canyon of the Colorado River in northwestern Arizona, where they overlie the strongly deformed and contorted Vishnu Schist, the angularity of which stands in bold contrast to the almost horizontal bedding of the Grand Canyon Series. The Grand Canyon Series actually dips slightly eastward and is separated from the overlying Cambrian sandstones by a major erosion surface unconformity. A conglomerate was deposited on the eroded surface of the Vishnu Schist. Limestones, shales, and sandstones occur over the conglomerate and are thought to represent shallow water deposits. The area of deposition was probably a large deltaic region that was slowly subsiding, allowing great thicknesses of sediment to accumulate near sea level . The presence of Precambrian organisms is indicated by calcareous algaelike structures in the carbonate rocks, as well as by tracks and trails of wormlike creatures in other rocks. Initially, in a generalized outline of the Precambrian history of the region, the Vishnu Schist was upraised, folded, and metamorphosed and then slowly eroded and worn down to a flat surface. The Grand Canyon Series was deposited perhaps as part of a slowly subsiding geosynclinal trough. The region was then subjected to uplift and tilting, and a Precambrian period of erosion for the Grand Canyon Series began. This action was later followed by a long period of deposition during the Paleozoic Era (540 to 245 million years ago) and then further erosion during the Cenozoic Era (beginning 66.4 million years ago) until the region assumed its modern configuration.
|Copyright© 2005 - 2021 | Trimite referat | Harta site | Adauga in favorite