This cycle is still continuing...
Ancient Greenland was actually green!
DNA analysis reveals ice-covered country was once home to butterflies.
The oldest ever recovered DNA samples have been collected from under more than a mile of Greenland ice, and their analysis suggests the island was much warmer during the last Ice Age than previously thought.
The DNA is proof that sometime between 450,000 and 800,000 years ago, much of Greenland was especially green and covered in a boreal forest that was home to alder, spruce and pine trees, as well as insects such as butterflies and beetles.
http://www.msnbc.msn.com/id/19619301/Ancient cemetery found in 'green' Sahara Desert.
WASHINGTON — A tiny woman and two children were laid to rest on a bed of flowers 5,000 years ago in what is now the barren Sahara Desert.
The slender arms of the youngsters were still extended to the woman in perpetual embrace when researchers discovered their skeletons in a remarkable cemetery that is providing clues to two civilizations who lived there, a thousand years apart, when the region was moist and green.
http://www.usatoday.com/tech/science/2008-08-14-green-sahara-cemetery_N.htm.Egyptian Prehistory..
Seven or eight thousand years ago, at the farthest reaches of human memory, before there was Egypt or the pyramids, North Africa was a lush and green place. There were vast grasslands and green forests stretching from the Atlantic Ocean to the Red Sea. Over this enormous green area, humans wandered in small groups; eventually, about eight thousand or so years ago, some of these small groups began to plant and cultivate their food. You might say that this change, which happened so slowly that it probably took a millenium to take place, was the single most important event in human history. For it turned humans into agriculturalists. As farmers, these wandering human groups settled down in one place, and human culture, confined now to villages, radically changed shape.
snip/
This is where the great Nile civilizations were fostered and grew: Egypt, Nubia, Meroe. From the desperate human communities forced by the growing desert to live on the banks of the Nile grew one of the first great urban cultures of human history. However, we know almost nothing of these early pre-Egyptian communities. What did they think? What gods did they worship? How did these communities evolve into the great urban centers of the Nilotic kingdoms? Like the grass and trees swallowed by the desert, we'll never know,
http://www.wsu.edu/~dee/EGYPT/PREHIST.HTM