[Junior]

Just to doublecheck the numbers, you've put the average depth of the Grand Canyon at 2000 feet (I've heard some section are as much as a mile deep, but 2000 feet sounds like a good average). Over 35,000,000 years the river would only have to wear an average of 0.017 mm of rock per year -- thinner than a sheet of paper. It seems to me that natural water erosion should be more than sufficient to account for the canyon we see today. Your theory is interesting and all, but it lacks any evidence of a static electrical discharge (fused sand, etc.) necessary to corroborate it; and without that evidence the other hypothesis (water erosion), which does have evidence supporting it, appears to be the best explanation for the canyon we have.

[medved]

Just to doublecheck the numbers, you've put the average depth of the Grand Canyon at 2000 feet (I've heard some section are as much as a mile deep, but 2000 feet sounds like a good average).

The 1500' - 2000' number I was throwing out is not the depth of the thing but only the visual impression one gets of how far the thing goes more-or-less straight down before starting to slope inwards at all.

Reading about this one in books doesn't get it. If you've never seen it up close, you need to. The most major impression you get is of the sharp and jagged and pristine look of all the rocks in that initial 1500' drop. Rivers don't do that. If the thing had been cut by water, it would be totally smooth. The thing basically defies any sort of uniformitarian geology.