هل كانت بلاد العرب مروجاً وأنهاراً؟ - المراجع العلمية

ENCYCLOPEDIA BRITANNICA:

1- Last Glacier Age:

A most distinctive aspect of the last ice age, the Pleistocene Epoch (from 1,600,000 to 10,000 years ago), was the recurrent expansion and contraction of the world's ice cover. These glacial fluctuations influenced geological, climatological, and biological environments and affected the evolution and development of early humans. Pleistocene chronology is based primarily on ice-sheet fluctuations. Almost all of Canada, the northern third of the United States, much of Europe, all of Scandinavia, and large parts of northern Siberia were engulfed by ice during the major glacial stages. At times during the Pleistocene Epoch, glacial ice covered 30 percent of the world's land area; at other times the ice cover may have shrunk to less than its present extent.

2- Changing environments in response to climatic variation caused drastic disruptions of faunas and floras both on land and in the oceans. These disruptions were greatest near the former ice sheets that extended far to the south and caused the southward displacement of climatic and vegetation zones.

In the temperate zones of central Europe and the United States where deciduous forests exist today, vegetation was open and most closely resembled the northern tundra, with grasses, herbs, and few trees during glacial intervals. Farther south, a broad region of boreal forests with varying proportions of spruce and pine or a combination of both extended almost to the Mediterranean in Europe and northern Louisiana in North America.

3- Little Ice Age:

A number of major ice ages have occurred throughout Earth history.

The earliest known took place during Precambrian Time dating back more than 570 million years.

The most recent periods of widespread glaciation occurred during the Pleistocene Epoch (1,600,000 to 10,000 years ago).

A lesser, recent glacial stage called the Little Ice Age began in the 16th century and advanced and receded intermittently over three centuries. Its maximum development was reached about 1750, at which time glaciers were more widespread on Earth than at any time since the principal Quaternary Ice Ages.