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FOSSIL LIMESTONE #1
Biosparite Go on to: #1 | #2 | #3 | #4 
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Composition
Fossils, some whole some fragmented, cemented by a spar matrix (crystalline calcite). Most of the fossils are crinoid stem fragments, but favositid (honeycomb) corals and stromatoporoids are also common.
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Description
Coarse, rough rock with abundant fossils weathering out. Simplistically it is a fossil limestone, but technically it is called a packed biosparite. Packed because it is packed full of skeletons, bio=fossils, sparite=calcite cement between the skeletons. This is also a corase, poorly sorted rock, with skeletons of many different sizes jumbled together. A number of scours, erosion surfaces, are also visible indicating periods of very strong currents, most likely storms.The next several images will take you in closer and closer to the rock, primarily on the left side of the outcrop. Clicking the pictures will cycle you through them. |
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Tectonic Association
Carbonates of all types are commonly associated with regions of tectonic stability and tropical climates, that is no mountain building, and stable, shallow water environments associated with continental shelves or epeiric (epicontinental) seas.Go to Carbonate Tectonics for more explanation. |
Formation & Environments
This outcrop is either a reef, or is closely associated with a reef. It was a high energy environment as indicated by the lack of fine grained sediment (micrite), and the presence of spar cement. Spar is crystalline calcite crystals precipitated by ground water in the spaces between the fossils after deposition.Before this became a rock we can imagine it as a rubble pile of skeletons lying on the bottom with no other sediment intermixed with them. |
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