Ur, the home city of Peleg (Abraham's great great great great grandfather) was excavated by the archaeologist Sir Leonard Wooley in the 1920's. During the course of the excavation, he discovered a layer of clay some 8 feet or 2.5 m deep. This could only have been deposited by a catastrophic river flood.
Flood legends exist the world over, for the very simple reason that the last glacial maximum occurred some 20,000 years ago and sea levels rose several hundred feet to their present level by approximately 10,000 BC.
There is evidence that the Black Sea flooded suddenly when a wall a debris forming a dam in the Bosphoros burst. The Mediterranean Sea seems to have been several hundred feet higher than the level of the Black Sea. The effect of this must have been astonishing to anyone who lived on the banks ot the Black Sea and would have formed the basis of legend throughout the near east.
Many cultures throughout the world have their flood myths but the flooding in Mesopotomia discovered by Sir Leonard Wooley is unlikely to have been anything other than a relatively localised event.
The formation of the Grand Canyon is well established by geologists. It was not affected by glaciation (or the valleys would have the distinctive U-shape) and neither was it significantly affected by a flood in historical time.