Thursday, February 28, 2008

Keeping some houses out of the river today.


I worked in St. Louis County (Missouri) today to look at the geomorphology of a creek threatening a few houses. As is often the case, this one is a political stew and I can't say much more except that this was a bad spot for a subdivision. But of course the developer is long gone.

The site is subject to backwater from the Meramec River and also carries a high coarse sediment load, exacerbated by erosion of chert-residuum-rich bank materials upstream. Very interesting management problem. Thanks to Dan for the photo of me being puzzled by the bank stratigraphy. A mix of loess, limestone residuum with chert residuum, and eroded and deposited layers of these materials. A lot happened at the junction of the Illinois, Missouri, and Mississippi Rivers during the Pleistocene.





That reminds me, the ISGS has a stunning 1909 map of St. Louis area geology online (small excerpt here)--from their 1909 bulletin 12, Physiography of the St. Louis area, by N. M. Fenneman. It's a 9mb PDF download. There's also a nice map of a tortuous 1909 meander sequence of the Mississippi just itching to be straightened out here.

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