The increase in discharge can be triggered by several events. The most common cause of flooding is prolonged rainfall. If it rains for a long time, the ground will become saturated and the soil will no longer be able to store water leading to increased surface runoff. As well as prolonged rainfall, brief periods of heavy rain can also lead to floods.
An Outline of American History "Heaven and Earth never agreed better to frame a place for man's habitation. As a result, the Bering Sea was hundreds of meters below its current level, and a land bridge, known as Beringia, emerged between Asia and North America.
At its peak, Beringia is thought to have been some 1, kilometers wide. A moist and treeless tundra, it was covered with grasses and plant life, attracting the large animals that early humans hunted for their survival. The first people to reach North America almost certainly did so without knowing they had crossed into a new continent.
They would have been following game, as their ancestors had for thousands of years, along the Siberian coast and then across the land bridge. Once in Alaska, it would take these first North Americans thousands of years more to work their way through the openings in great glaciers south to what is now the United States.
Evidence of early life in North America continues to be found. Little of it, however, can be reliably dated before 12, B. So too may the finely crafted spear points and items found near Clovis, New Mexico. Similar artifacts have been found at sites throughout North and South America, indicating that life was probably already well established in much of the Western Hemisphere by some time prior to 10, B.
Around that time the mammoth began to die out and the bison took its place as a principal source of food and hides for these early North Americans. Over time, as more and more species of large game vanished -- whether from overhunting or natural causes -- plants, berries and seeds became an increasingly important part of the early American diet.
Gradually, foraging and the first attempts at primitive agriculture appeared. Indians in what is now central Mexico led the way, cultivating corn, squash and beans, perhaps as early as 8, B.
Slowly, this knowledge spread northward. Then the first signs of irrigation began to appear, and by B. By the first centuries A. They began constructing earthen burial sites and fortifications around B. Some mounds from that era are in the shape of birds or serpents, andprobably served religious purposes not yet fully understood.
The Adenans appear to have been absorbed or displaced by various groups collectively known as Hopewellians. One of the most important centers of their culture was found in southern Ohio, where the remains of several thousand of these mounds still remain.
Believed to be great traders, the Hopewellians used and exchanged tools and materials across a wide region of hundreds of kilometers. By around A.
One city, Cahokia, just east of St. Louis, Missouri, is thought to have had a population of about 20, at its peak in the early 12th century.
At the center of the city stood a huge earthen mound, flatted at the top, which was 30 meters high and 37 hectares at the base. Eighty other mounds have been found nearby.
Cities such as Cahokia depended on a combination of hunting, foraging, trading and agriculture for their food and supplies. Influenced by the thriving societies to the south, they evolved into complex hierarchical societies which took slaves and practiced human sacrifice.
In what is now the southwest United States, the Anasazi, ancestors of the modern Hopi Indians, began building stone and adobe pueblos around the year These unique and amazing apartment-like structures were often built along cliff faces; the most famous, the "cliff palace" of Mesa Verde, Colorado, had over rooms.
Perhaps the most affluent of the pre-Columbian American Indians lived in the Pacific northwest, where the natural abundance of fish and raw materials made food supplies plentiful and permanent villages possible as early as 1, B. The opulence of their "potlatch" gatherings remains a standard for extravagance and festivity probably unmatched in early American history.
It is now thought that as many people lived in the Western Hemisphere as in Western Europe at that time -- about 40 million. Estimates of the number of Native Americans living in what is now the United States at the onset of European colonization range from two to 18 million, with most historians tending toward the lower figure.
What is certain is the devastating effect that European disease had on the indigenous population practically from the time of initial contact.
Smallpox, in particular, ravaged whole communities and is thought to have been a much more direct cause of the precipitous decline in Indian population in the s than the numerous wars and skirmishes with European settlers. Indian customs and culture at the time were extraordinarily diverse, as could be expected, given the expanse of the land and the many different environments to which they had adapted.
Some generalizations, however, are possible.News of the fertility of the Connecticut River Valley, for instance, attracted the interest of farmers having a difficult time with poor land. By the early s, many were ready to brave the danger of Indian attack to obtain level ground and deep, rich soil.
The Great Gatsby by F. Scott Fitzgerald. Home / Literature / The Great Gatsby / Analysis / Long Island and New York City in the Early s. while the women are left behind.
This geographical divide ends up being a gender distinction, too. But the city is important in other ways, too; Tom only interacts with his mistress in the city. Type or paste a DOI name into the text box.
Click Go. Your browser will take you to a Web page (URL) associated with that DOI name. Send questions or comments to doi. GLOBAL REGENTS REVIEW PACKET NUMBER ONE - PAGE 2 of 16 • ARCHAEOLOGISTS study the physical artifacts of a culture.
• POLITICAL SCIENTISTS study the origin, development, and operation of political systems and public policy. • SOCIOLOGISTS study society and social behavior by examining the groups, cultures, organizations, and social institutions people form.
China Geography Located in Southeast Asia along the coastline of the Pacific Ocean, China is the world's third largest country, after Russia and Canada. With an area of million square kilometers and a coastline of 18, kilometers, its shape on the map is like a rooster.
acquired trait: A phenotypic characteristic, acquired during growth and development, that is not genetically based and therefore cannot be passed on to the next generation (for example, the large.