Message #61642

[Bianca]

The following year Dr. Ewing again went out on two additional cruises staying out over the MAR for over 4 months covering the area from the latitude of Newfoundland to almost down to the bulge of South America. One of the more puzzling discoveries on this second cruise was the discovery of…

...prehistoric beach sand in two core samples of the bottom, brought up in one case from a depth of two and in the other nearly three and one-half miles, far from any place where beaches exist today. In one case there were actually two layers of sand, one 20,000 to 100,000 years old and the other 225,000 to 325,000, these ages being calculated from the depth and the average rate at which sediment is deposited.11

Dr. Ewing offers two "startling" theories on how that beach sand got there:

Sometime in the distant past this sand, found deep beneath the ocean, must have been located on a beach, at or near the surface of the sea. Either the land must have sunk two to three miles, or the sea must have been two to three miles lower than now. Either conclusion is startling. If the sea was once two miles lower, where could all the extra water have gone? Some sand found in other places on the Atlantic bottom undoubtedly was rafted out from shore by floating ice during past glacial periods. But the grains in the sand we found are well sorted into various sizes, with no large fragments. This fact suggests that here is a real beach, unless the sand was originally picked up from a beach by the ice which is extremely unlikely. One of the sand deposits is 1,200 miles from land and so far south that it is improbable that ice could ever have carried sand that far before melting.12

In other words, a part of the Atlantic Ocean, 1,200 miles from land, had to be a beach at one time.

Again Dr. Ewing mentions how they had checked sediment depths in "more than 3,000 different places over vast areas of the Atlantic." While there are

thousands of feet of sediments on the foothills of the Ridge, surprisingly, however, we have found in the great flat basins on either side of the Ridge this sediment appears to be less than 100 feet thick, a fact so startling that it needs further checking.13

So it seems that as far back as the first scientific expedition over the MAR there was already some evidence that some areas of the MAR may have sunk in pre-historic times.