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Characteristic olive residuum and white caliche nodules of the Mooreville Chalk |
Mooreville Chalk
Residuum exposed in ditches along private roads is from the underlying Mooreville Chalk. Note the characteristic olive residuum and the white caliche nodules.
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Characteristic olive residuum and white caliche nodules of the Mooreville Chalk |
Highly inclined sedimentary beds in abandoned borrow pit
This stop is a visit to one of several abandoned borrow pits in the interior of the impact structure that expose steeply inclined, sedimentary beds of the Cretaceous formations. Steeply dipping beds are exposed here. The rock strata would not normally be deposited at this angle of repose, nor would deposition produce such irregular relationships.
This borrow pit apparently contains only red and tan colored Tuscaloosa Group (fluvial and overbank) sediments, with small embedded blocks of schists up to one meter long. The interpreted photomosaic shows four megablocks 10s of meters across, each distinguished by sheared marginal discontinuities and differing strikes and dips of beds within. In megablock B we are looking at the tops of the beds from our observation position on the western rim of the borrow pit. This megabreccia was likely an early transient rim slump deposit constituting the crater melange.
The borrow pit contains a clayey sandy unit of the Eutaw Formation.
The Eutaw is distinguished by
white, clay lined Ophiopmorpha burrows
that may be seen at this outcrop.
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White clay-lined Ophiomorphia burrows in Eutaw formation. |
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