Prehistoric archaeologists are trying to document and understand the ways in which humanity adapted itself to the diverse environments of the world. We humans are the only animals to use our culture, the sum total of ways of living, as the primary means of adopting to our environment. Therefore studying these adaptations can bring about an understanding of the diversity of human cultures that made up the prehistoric world. A study of the environment includes the relationship of climate, vegetation and animal existence.
The Pleistocene, more commonly called, the Glacial Epoch or Ice Age, was an age of widely fluctuating climate with major shifts in temperature occurring thousands of years apart. During this time North America went through many changes. The sea level fell because much of the water that might have been in the oceans was locked up in the glaciers. This process is called eustasis. The sea level was from 50 to 300 feet lower than it is now. The actual shoreline at that time extended 100 kilometers out onto the continental shelf, exposing a broad highway between Asia and North America, This Berengian landmass was well above sea level for very long periods of time. The exposed shelf was one vast region of low, gentle, rolling plains covering thousands of square miles from the Aleutian Islands in the south to latitudes way up in the Arctic Ocean.
MAP I
(figure available in print form)
There have been a number of ice ages in the earth’s history their cause is unknown. It was once thought that some kind of solar shift allowed less heat energy to reach the earth, thus causing a cooling of world climates and snow fall in amounts greater than the summer melt-off. Another theory is that there was a change in the atmosphere that either blocked heat energy from reaching the earth, or allowed a greater reflection of light from the earth’s surface and thus a loss of heat back into space.
The Pleistocene was also a period of vigorous volcanic activity. Volcanic ash in large amounts in the upper atmosphere may well have been the cause for the lowering of world temperatures. Some scientists believe modern air pollution on a worldwide basis may eventually have the same effect.
In North America the Glacial Epoch extends back in time from about 10,000B.C. to 1,000,000, B.C. During this time the ice sheet advanced and receded as the climate changed from cold to warm and back again. During this period much of North America was as cold as Greenland today, as great ice sheets moved down out of Canada. (chart II) The most recent glacial advance was the Wisconsin, which is thought to have begun about 70,000 years age. The ice sheet extended about as far south as the present location of the Ohio River and then east as far as Long Island. At the height of the glacial advance the ice cap was more than a mile thick (map II)
The Connecticut area, for most of the Pleistocene Era, was covered with ice or severely affected by it. In approximately 17,000 B.C. the Wisconsin Glacier reached Long Island, its farthest advance southward. The glacial ice has been estimated to have been about 1,900 feet thick over the New Haven area and about 2,500 feet thick over the Hartford area. Since much of the ocean water was locked up in the ice, most of Long Island Sound was a dry valley with Long Island as part of the mainland. (map III)
The region south of the glacier had a much cooler and wetter climate than today. Many areas of the present United States that are now barren desert were green, watered and well stocked with animals. The Great Salt Lake in Utah is all that remains, of a huge body of salt water called Lake Bonnevill that covered much of Utah, Nevada and Idaho. (map II)
CHART II—THE ICE AGE—GLACIAL EPOCH—PLEISTOGENE
(figure available in print form)
MAP II—NORTH AMERICA DURING THE WISCONSIN GLACIER
(figure available in print form)
MAP III—CONNECTICUT AT THE HEIGHT OF THE WISCONSIN GLACIER
As the ice sheet advanced southward, animals were driven before it. A strange assemblage of animals now extinct-the giant ground sloth, giant beaver, mastodons, wooly mammoth, saber tooth cat, native camels, horses, and a huge species of bison—mingled on the lush grasslands, woods and marshes south of the glacier. With them were the wolves, bear, deer, antelope and rabbit which have survived essentially unchanged to this day. The remains of these animals help palaeontologists to construct a picture of the natural environment of the time. It was into this environment that man arrived in North America.