Pastwatch- The Redemption Of Christopher Columbus - By Orson Scott Card Page 0,30

was part of the effort to determine how the Red Sea might be exploited to develop dependable rains for the Sudan and central Arabia; Kemal's immediate target was to study the difference between weather patterns during the last ice age, when the Red Sea had all but disappeared, and the present, with the Red Sea at its fullest. Back and forth he went through the coarse old Pastwatch recordings, gathering data on sea level and on precipitation at selected points inland. The old TruSite I had been imprecise at best, but good enough for counting rainstorms.

Time after time Kemal would cycle through the up-and-down fluctuations of the Red Sea, watching as the average sea level actually rose toward the end of the Ice Age. He always stopped, of course, at the abrupt jump in sea level that marked the rejoining of the Red Sea and the Indian Ocean. After that, the Red Sea was useless for his purposes, since its sea level was tied to that of the great world ocean.

The echo of Schliemann inside Kemal's mind made him think: What a flood that must have been.

What a flood. The Ice Age had locked up so much water in glaciers and ice sheets that the sea level of the whole world fell. It eventually reached a low enough point that land bridges arose out of the sea. In the north Pacific, the Bering land bridge allowed the ancestors of the Indies to cross on foot into their great empty homeland. Britain and Flanders were joined. The Dardanelles were closed and the Black Sea became a salty lake. The Persian Gulf disappeared and became a great plain cut by the Euphrates. And the Bab al Mandab, the strait at the mouth of the Red Sea, became a land bridge.

But a land bridge is also a dam. As the world climate warmed and the glaciers began to release their pent-up water, the rains fell heavily everywhere; rivers swelled and the seas rose. The great south-flowing rivers of Europe, which had been mostly dry during the peak of glaciation, now were massive torrents. The Rhone, the Po, the Strimon, the Danube poured so much water into the Mediterranean and the Black Sea that their water level rose at about the same rate as that of the great world ocean.

The Red Sea had no great rivers, however. It was, in geological terms, a new sea, formed by rifting between the new Arabian plate and the ancient African, which meant it had uplift ridges on both coasts. Many rivers and streams flowed from those ridges down into the Red Sea, but none of them carried much water compared to the rivers that drained vast basins and carried the melt-off of the glaciers of the north. So, while the Red Sea gradually rose during this time, it lagged far, far behind the great world ocean. Its water level responded to the immediate local weather pattems rather than to worldwide weather. Until one day the Indian Ocean rose so high that tides began to spill over the Bab al Mandab. The water cut new channels in the grassland there. Over a period of several years, the leakage grew, creating a series of large new tidal lakes on the Hanish Plain. And then one day, some fourteen thousand years ago, the flow cut a channel so deep that it didn't dry up at low tide. The water kept running through it, cutting the channel deeper and deeper, until those tidal lakes were fall, and brimmed over. With the weight of the Indian Ocean behind it the water gashed into the basin of the Red Sea in a vast flood that in a few hours brought the Red Sea up to the level of the world ocean.

This isn't just the boundary marker between useful and useless water level data, thought Kemal. This is a cataclysm, one of the rare times when a single event changes a vast area in a period of time short enough that human beings could notice it. And, for once, this cataclysm happened in an era when human beings were there. It was not only possible but likely that someone saw this flood -- indeed, that it killed many, for the southern end of the Red Sea basin was rich savanna and marshland up to the moment when the ocean broke through, and surely the humans of fourteen thousand years ago would have hunted there. Would have gathered seeds and fruits and berries there. Some