摘要：The hydrologic system in Jordan began its evolution with the regression of the Tethys during the Eocene and the rifting of Arabia from Africa. From that time onward Jordan lay on land. The rivers from Jordan and the Sirhan east of it flew into the Rift. On the Jordan land volcanism developed and was on and off active until sub-recent times. Flows of magma covered large areas in north and central Jordan. The uppermost hard layers of the deep valleys of the Yarmouk and the Mujib present evidence for their later erosion. The land to the east of the rift was low and in depressions lakes formed on the Jordan plateau, which began to rise less than half a Million years ago. Especially the Jafr and the Azraq Lakes developed a belt of green vegetation that attracted numerous animals which were hunted by early men. Tools for hunting and food preparation were produced from flint and assembled next to the former lake shores with time. The shape of these flint tools allows a coarse dating and documents the arrival of humans hundred thousand years ago and of modern men between 50,000 and 80,000 years ago. Great changes in the shape of the eastern Rift margin had occurred before Lake Lisan evolved and its rising water flooded the mouths of canyons for example of Wadi Hasa, Wadi Mujib and Wadi Zerka Ma’in. On former gravel fans into Lake Lisan of the Tabaqat Fahl first agriculture still in Neolithic times evolved as well as in Amman where people from Ain Ghazal planted crops like barley and peas, beans, lentils and chickpeas and domesticated sheep, goats and pigs. The existence of the highland lakes seems to have been of utmost importance to human migrations from Africa. Such lakes provided water and food for those humans in the Arid area of Jordan.
