Carboniferous Limestone with crinoids
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Fact sheet
Description: 

This Lower Carboniferous limestone contains many fragments of crinoid ossicles that were once the stems of ancient marine animals attached to the sea bed, sometimes called sea lilies. There are also many fragments of brachiopod shells. The sample comes from Bucket Rocks, Berwick upon Tweed, England, and is cemented by a carbonate rich mud.

The thin section is dominated by two species of crinoid ossicles, both in longitudinal section and cross section. One species has a circular cross section, the other has a five-sided form. The crinoids have a dusty appearance due to the microcrystalline nature. Fragments of brachiopod shells are marked out by more transparent crystalline calcite. The cement ranges from blocky carbonate grains to fine-grained calcium-rich mud.

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In Time
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Location description: 
Bucket rocks, Berwick on Tweed, Berwickshire
Accuracy:
Location precision: 
Good
Timescale:
Timescale: 
Carboniferous
Ma = Millions of years ago
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Type: 
sedimentary
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