CompuServe Messages

>>Yes thats it but they continue on down some go on down to 3,000 meters like there was no water down at that level for at least a short period of time. However, if they existed prior to the opening of the Atlantic Ocean in the Mesozoic, the rivers would have continued headward erosion and never been submerged. Also, erosion can take place in a sub-aqueous environment. River currents can extend long distances into the ocean. There are freshwater currents associated with the Amazon that extend at least 50 miles past the mouth of the river. Similar currents are associated with the Mississippi, and Columbia, and the is anecdotal evidence for the same situation before the Colorado was dammed to nothingness. Sub-aqueous erosion is not as rapid as sub-aerial, but it does take place. Cosidering that the continental shelves have been in roughly their present configuration for 65 million years, there is bound to be headwatd erosion in any canyon. Jim