Sand RBGPSW 26-31 Patterns in the sand with wave-distributed black sediment on the low-tide seashore at Rhossili Bay in Gower, South Wales April 2017
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Jessica's Nature Blog 
Very interesting photographs. What does the black sediment consist of Jessica?
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Hello, Trevor. On this occasion the black sediment was mostly made up of small pieces of wood, coal, and fish bones. The greyer stuff was crushed shell. I took a sample home and looked under the microscope.
https://natureinfocus.blog/2017/05/13/composition-of-black-sediments-at-rhossili/
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