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DerelictJunction
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Flood level water flowing down the river through the meanders would erode the sides more than it would cut the canyon deeper. The speed of the water would not change so no increase in the erosion rate on the bottom of the canyon would occur. I don't have the calculations to prove that, but no change in gravity and nothing to push the water faster seems to support that conjecture.If that's not your argument, then you should learn to make arguments that are clear, concise, and easily understood.
You say that it takes a long time for incised meanders to form to the depth that a large flood would not ruin them. Who was talking about a large flood? I merely pointed out that the Grand Canyon is prone to flash floods. During the so-called "monsoon" season the Grand Canyon might experience a flash flood every week or even every day.
A simple look at:
shows that the water level is quite low. I'm no expert, but I eyeball that this meander could hold 5-10 times the quantity of water currently flowing through it without overflowing the banks.
So when you say that "we [can] know [whether] erosion rates in the past were higher for the same water flow" you are making a big assumptionthe same water flow. Flash floods can and do move larger quantities of water through these channels on a regular basis.
No one can know whether these floods were more common or less common in the past than they are now. No one knows how much plucking may have occurred. Uniformitarian assumptions are just that: assumptions. No one knows whether they are true.
Maybe extra sediment would have some effect.
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