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| Oxbow Lake with Meander Cutoff |
As Joan explains (rather long-windedly), an oxbow lake is
"Oxbow lakes are u-shaped bodies of water that are formed from the bend in a river that was cut off from the river's flow at some point in time...."
...not that you need that "at some point in time"; it wouldn't be a lake unless it was no longer part of the channel, would it! Joan goes on to explain, sort of, that rivers do something called "meander." According to Joan, the reason rivers meander is because..."...[a] meander allows the river to handle more water in less acreage, and feed all that water into the ocean without flooding the flood plains on non rainy days..."Well, we'd hope the river doesn't flood on rainy days, either, Joanie! And by the way, have you ever heard of rainy seasons vs. wet seasons? Monsoons? Snow melt? We didn't think so... Now, let's see how Whetzel "explains" the formation of an oxbow lake. Wanna bet she gets it wrong? |
"Rivers pick up rocks along the way, which break down into smaller rocks and pebbles, and then silt, all of which get carried downstream. Rivers also pick up more silt from the river bed as the water makes its way from higher altitudes down to seal [sic] level. All of this debris, as you may well imagine, can clog the river way, especially when the water levels are low from lack of rain. If the river's curve is very thin, the silt can choke it off al together [sic] from the main flow, creating an oxbow lake that is no longer part of the river."
| Well, we asked our staff geologist if what Whetzel said is correct. He just laughed and said, "Joan Whetzel again?" In reality, Joan has everything pretty much bass-akwards. Oh, the kindergarten-level crap about eroding big rocks and turning them into little rocks is more or less correct. But that part about "If the river's curve is very thin, the silt can choke it off al together [sic]"? That, dear readers, is utter bullshit. You see, meanders form where a river is carrying a large sediment load and the landscape is (relatively) flat. The river lacks the energy to carry all that sediment, so it drops some of it. Still, the water in the channel "wants" to keep going downhill, so it detours around the abandoned sediment. This develops a cycle: the running water is faster on the outside of a bend than the inside, so wherever there is a curve in the channel – a meander – the water in the river erodes on the outside of the curve and deposits sediment (eroded from upstream) on the inside. An oxbow forms when two meanders carve into each other from opposite directions and connect, shortening the path the channel takes. The abandoned meander, and that's what an oxbow lake is, forms a swampy area that eventually fills up with sediment. |
 
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About all Whetzel got right here is that rivers meander, though she was even a little confused about that, too; describing the Brazos River near her Houston-area stomping grounds as having "a wonderful meander patter [sic]." Given her well-proven inability to synthesize information from sources and to present it in a cogent matter, is it any wonder that Joan takes the lead in dumbassery, collecting her eighteenth Dumbass of the Day award? that's 3.6% of the awards we've handed out so far, though Joan would probably get that calculation wrong, too... |
¹ The post has been deleted, and archive.org's Wayback machine never made a copy of the post. Oh, well, no loss...
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SI - GEOLOGY
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