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| ©RomaniaRocks |
I am a geologist, so is my SO, and this weekend we enjoyed a trip along the Trinity River; beautiful weather was a plus, and it made it for a great family outing. We started with our canoe from the bridge across Trinity near Liberty, TX. From here we went north for about 7 km in total (the red line shows our path for the day).
The first stop was on the opposite bank from the meander loop cut-off, indicated by the yellow arrow in the picture above. A point bar with a lot of awesome features, worthy of any Geology 101 class: ripples and dunes...
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| ©RomaniaRocks |
... with awesome lineation in the coarse grain fraction oriented parallel to the transport direction (downstream is towards the top of the picture).
More ripples and dunes...
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| ©RomaniaRocks |
... mud cracks and the resulting mud-chips waiting for the next bank-full discharge to be washed away....
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| ©RomaniaRocks |
... unless of course your teenager will not remove them all by building mud-chip castles.
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| ©RomaniaRocks |
The mud cracks on the surface of this point bar developed in low areas, when water level was just above the edge of the depression where the mud accumulated. Eddies formed in these low areas of the point bar, and these eddies brought in and deposited a thin layer of mud. The mud cracks formed later after the water receded and the surface dried out. Similar eddies carrying and depositing fine-grained material (but at a larger scale) were responsible for the deposition of a nice mud-drape on one of the point bars we stopped at further upstream. The picture below shows the river bank with the water flow from right to left, and a protected area entered by an eddie, which deposited a beautiful mud-drape over the extent of the point bar exposure (arrows indicate the extent of the mud drape).
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| ©RomaniaRocks |
Well developed cross-bedding may be seen within the point bar succession....
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| ©RomaniaRocks |
... and ripple lamination, cross-bedding and wind ripples may be found in the right exposures on the point bars...
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| ©RomaniaRocks |
We had a blast: great weather, nice river, good canoeing, and cool sedimentary features. You get the picture :)
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