I am attempting to interpret an outcrop I went to. I suggested it was created by a braided stream. The one thing I cannot explain are prominent alternating siltstone and sandstone beds. There are smaller lenses of silstone that I suggest are abandoned channel fills, but I have other siltstone beds about 0.2 - 0.5 m thick that seem pretty continuous (laterally continuous up to ~ 10-15 m as far as I can see).
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Peter Jansson
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PattyWatty27
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2It would be great if you could provide a picture to help us get a good insight – marsisalie Dec 05 '19 at 15:53
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without images this description is pretty merger and makes helping you difficult. A picture is worth a thousand words and you don't have many words ot begin with. – John Dec 06 '19 at 16:00
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@EtienneGodin Here is a photo! – PattyWatty27 Dec 27 '19 at 05:31
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Any more hints, where is it, and when is it ? – Dec 27 '19 at 15:08
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Braided channels are usually found in estuaries. Estuaries are usually on the coast. That being the case, it seems possible that now and again a high tide brought in some sand which covered the silt-filled channels, which then brought more silt, thus creating the layered structure you describe. If the site is now a long way from the coast, it doesn't follow that it always was.
Michael Walsby
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4Braided channels are not restricted to coastal environments. They are also common in mountain/glacial settings, although in those cases you should find coarse grains, i.e. gravels, not only silt/sand. – Jean-Marie Prival Nov 06 '19 at 13:11
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Not a specialist, but i was under the impression that they are usually indicative of the proximal reaches, where sediment load and slope are high. But i may be wrong and can't contribute more without guessing ... – Dec 05 '19 at 13:05
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3The channels of many North American Prairie rivers (e.g. the Platte) were naturally braided until engineers got to them. – Spencer Jan 16 '22 at 01:38