Ah good ol Talk Origins.
Yes, I got the figure from Austin's book, and Percy has confirmed it himself although of course he says things have changed so it no long applies. And besides the river erodes areas outside the canyon. Well, Austin says the same, and emphasizes that it's no longer eroding the canyon but the Colorado plateau above the canyon. His main question was the one that has been posed to me: Where is all the eroded material? That's a LOT of eroded material, certainly a million cubic miles of the stuff but even the scaled-down version Percy came up with. Where did it all go?
But Talkorigins raises the usual silly objections to the idea that the Flood carved the canyon, many I've already answered, so I thought I'd go through them and answer them again:
1. We know what to expect of a sudden massive flood, namely:
a wide, relatively shallow bed, not a deep, sinuous river channel.
Uh huh, wouldn't that depend on the kind of terrain the Flood was acting upon? The GC is cut into an uplift, something no river could have done all by its little self, since it would prefer to go around things that are higher than its little self. You get your wide relatively shallow beds on your flatter landscapes.
anastamosing channels (i.e., a braided river system), not a single, well-developed channel.
coarse-grained sediments, including boulders and gravel, on the floor of the canyon.
streamlined relict islands.
You mean like the Washington scablands? Right:
The Scablands in Washington state were produced by such a flood and show such features (Allen et al. 1986; Baker 1978; Bretz 1969; Waitt 1985). Such features are also seen on Mars at Kasei Vallis and Ares Vallis (Baker 1978; NASA Quest n.d.). They do not appear in the Grand Canyon. Compare relief maps of the two areas to see for yourself.
The terrain is decidedly different in the two places. You have basalt in Washington and sedimentary rock in Arizona, you have a relatively flat terrain in Washington but an uplift in the GC area that the Flood had to cut into, and only a huge amount of water might be able to do that, no ordinary river, even a big fastmoving river. I happen to think that the water that cut the canyon also cut the formations in the Grand Staircase to the north and eroded all the higher strata off the surface of the Kaibab plateau, and I don't think the lake water would be enough for that, although if the Colorado plateau is dish-shaped as Austin contends, which is how the lake he has in mind was contained, that could easily explain how the water was also able to cut the canyon whereas a mere river couldn't, since it would be contained on the plateau rather than running off it as one might otherwise expect.
2. The same flood that was supposed to carve the Grand Canyon was also supposed to lay down the miles of sediment (and a few lava flows) from which the canyon is carved. A single flood cannot do both. Creationists claim that the year of the Flood included several geological events, but that still stretches credulity.
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Dumtadumdum, isn't this the famous Argument from Incredulity that creationists get slapped down for? Somebody better let Talkorigins know they're out of line.
Anyway, there is no problem with the "same Flood" both laying down the strata and then at the very end as it is receding cutting the canyon. How silly of them to make such an objection.
3. The Grand Canyon contains some major meanders. Upstream of the Grand Canyon, the San Juan River (around Gooseneck State Park, southeast Utah) has some of the most extreme meandering imaginable. The canyon is 1,000 feet high, with the river flowing five miles while progressing one mile as the crow flies (American Southwest n.d.). There is no way a single massive flood could carve this.
No, but all that occurs on the flat plain above the main part of the canyon, and rivers DO meander on flat plains. The Flood waters would have dissipated after scouring off the plain first and then we'd have the river left over to meander across it. I do doubt all this assertion we've heard here that only very slow rivers make meanders, I rather suspect the river had some power to it and did some deep cutting of the meanders on this flat plain, but I can't prove so oh well.
4. Recent flood sediments would be unconsolidated. If the Grand Canyon were carved in unconsolidated sediments, the sides of the canyon would show obvious slumping.
I think probably a lot of it DID slump, starting with the first cracks in the uppermost strata. Tons of broken up strata would have caved into the cracks and been washed down to cut the canyon, eventually widening the canyon a great deal. But the stack was over two miles deep when the cutting would have begun, and one would expect that the weight and pressure should have done some solidifying of the sediments so that the walls that were left after the carving stayed put.
5. The inner canyon is carved into the strongly metamorphosed sediments of the Vishnu Group, which are separated by an angular unconformity from the overlying sedimentary rocks, and also in the Zoroaster Granite, which intrudes the Vishnu Group. These rocks, by all accounts, would have been quite hard before the Flood began.
Meaning what? I have a completely different idea of what happened beneath the canyon, but many creationists accept it as already formed before the Flood as reported here. But I still am not getting the point here about the supposed hardness of the rocks.
6. Along the Grand Canyon are tributaries, which are as deep as the Grand Canyon itself. These tributaries are roughly perpendicular to the main canyon. A sudden massive flood would not produce such a pattern.
How they trust their own weak little imaginations. A lot of water draining into cracks in the upper strata would cut out all kinds of cracks alongside the main one.
7. Sediment from the Colorado River has been shifted northward over the years by movement along the San Andreas and related faults (Winker and Kidwell 1986). Such movement of the delta sediment would not occur if the canyon were carved as a single event.
Why not?
8. The lakes that Austin proposed as the source for the carving floodwaters are not large compared with the Grand Canyon itself. The flood would have to remove more material than the floodwaters themselves.
This isn't very clear either. Not sure why the volume of water would have to be a large as the canyon itself in order to be an effective carving instrument. After all, if they think an ordinary river cut it, why not a flooding lake that is ALMOST the volume of the canyon. But my own view is that it was probably the receding flood waters themselves that cut the canyon. I do appreciate Austin's idea about the lake though because he says it would have been contained in the dish-shaped Colorado plateau, which means the flood waters would have been somewhat restrained from washing off the plateau as well, and available to cut the canyon. It's just a matter of more water. The lake water might nevertheless have been enough.
9. If a brief interlude of rushing water produced the Grand Canyon, there should be many more such canyons. Why are there not other grand canyons surrounding all the margins of all continents?
One must assume the circumstances were unique to the area.
10. There is a perfectly satisfactory gradual explanation for the formation of the Grand Canyon that avoids all these problems. Sediments deposited about two billion years ago were metamorphosed and intruded by granite to become today's basement layers. Other sediments were deposited in the late Proterozoic and were subsequently folded, faulted, and eroded. More sediments were deposited in the Paleozoic and Mesozoic, with a period of erosion in between. The Colorado Plateau started rising gradually about seventy million years ago. As it rose, existing rivers deepened, carving through the previous sediments (Harris and Kiver 1985, 273-282).
There's that seventy million years that would have produced that one million cubic miles of erosion. Funny they don't mention that as reported in Austin's book. If Percy's right that it's been officially reduced to five million years it's still a lot of erosion that nobody has been able to locate at the foot of the canyon.
Anyway, at least a Flood can produce sediments and layer them, but on that Rube Goldbergish scheme of billions of years you have to imagine this event and then that event without any source of sediments, you have to imagine uptilted rock being eroded down flat, you have to imagine that the tectonic upheaval occurred before the first horizontal layers were laid down and then not again until after the very last was laid down hundreds of millions of years later, and so on and so forth. But the Flood model has a very orderly sequence of events that explains it all.
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