From the BBC: Floodwaters create ‘Grand Canyon’
As you might expect, this news item popped up on my Google alerts because of great flood references. It’s now been mentioned on at least a couple of forums where people have an interest in, shall we say, Not Real Geology. I’m actually surprised I missed this entirely until it popped up on Google alerts. The BBC is my news source of choice. Then again, it’s an article from last Friday, and Fridays tend to be busy days for me.
So… oh noes! A big flood created a canyon-like structure. Take that, geologists!
This is basically the same deal as the Mt. St. Helens “canyon.” The River Wear flooded and carved a new (but apparently temporary) channel into its own flood plain. The “canyon” is about four meters deep at most, which means it runs entirely through unconsolidated floodplain sediment. Sediment on floodplains tends to be pretty fine – about mud sized. This is why flood plains make such prime agricultural real estate.
Now, it must be said that it is a bit surprising for a river to carve itself a new channel in a single flood. (Though the bigger the flood, the more believable this becomes.) The floodplain sediment isn’t consolidated, but the farther down you get, the more densely packed it will be due to the weight sitting on top of it. It’s not quite the same situation as the fresh ash layer at Mt. St. Helens.
However, this also may not be a new channel. Apparently locals think that this might actually be a disused channel of the river, which was diverted by monks in the 15th century. In that case, if it’s an old channel that was simply filled in by enterprising monks, the relatively new soil in the filled channel would probably be a lot easier for the river to wash away than the older soil of the flood plain.
So no. This is not any kind of evidence for a biblical flood. There’s still an enormous difference between a river cutting through unconsolidated sediment and cutting down through solid rock. It’s a pretty neat opportunity for anyone interested in the local soil, though.