> Does someone knows the meaning of such layers and some bibliography also?
Iron is soluble in anoxic water (Fe++) but precipitates as rust in oxidated water. A rusty coating could thus result from anoxic water from within the sediments mixing with oxygenated water from above as a mollusk burrows into the substrate.
Dr. David Campbell
Old Seashells
University of Alabama
Biodiversity & Systematics
Dept. Biological Sciences
Box 870345
Tuscaloosa, AL 35487-0345 USA
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That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa
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