Sunday, July 31, 2016

Geo 882: More Ball and Pillow... But Wait! There's More!

The more I look at this photo, the more little details I'm spotting. Starting with the colorful band of sediments near the top, one can tell from cross-cutting relationships that stratigraphic "up" is to the right. That gray, elongate blob on the bottom of the colorful package looks like a rip-up, a clot of semi-consolidated mudstone ripped from one spot and redeposited in another. It looks awfully big for the flow regime indicated by the surrounding sand, but I can't think of a better explanation.

In the crop below, I've highlighted one of maybe a half-dozen of ball and pillow structures in the photo, and a flame structure- the latter tend to be pointy in the stratigraphic upward direction. While ball and pillow represents denser sediment sinking, flame structures represent less dense sediment rising or being displaced upwards as ball and pillow structures form. Also, above and below those two structures, tafoni or honeycomb weathering can be seen. (We'll be seeing a LOT more of this in days to come.)
If you open the top photo up to full size and look around, you can find numerous small examples of minor soft sediment deformation.

Photo unmodified. July 21, 2016. FlashEarth location.

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