State by State
Louisiana
- Specimen Number
16
- Description
Block of rock with interbeds of limestone, with gray-blue alternating with brown-stained. Fizzes with dilute acid. Closeup shows granular texture with some finer-scale bedding and crystal regrowth in prisms normal to bedding planes. This is neither a limestone mud nor grainstone.
- Classification
Sedimentary. Limestone. Crystalline. Bedded.
- Location & Occurrence
For limestones in the state, the U.S. Geological Survey lists only "Upper Cretaceous fossiliferous limestone and marl" and "Wilcox Group.....some limestone and glauconite." Neither looks like our specimen. "Limestone occurs as part of the caprock at this dome, and as Cretaceous limestone brought to the surface by two salt domes in Bienville Parish." Quotes are from a Lousiana State Survey report compiled by Peggy B. Perazzo (see link below).
- Geological Age
Late Cretaceous.
- Geoheritage
Salt domes are fascinating and important features responsible for trapping much of the petroleum and gas for which Louisiana is well known. Yet the general public is virtually unaware of them. They rise slowly because salt is less dense than adjacent rocks, so it squeezes upward.
- Links
Link to State Geological Map from USGS. Link to Louisiana Geological Survey. Stone Quarries and Beyond.
- Other
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![Specimen stone for Louisiana.](https://earthsciences.media.uconn.edu/wp-content/uploads/sites/3541/2022/10/16a_Louisiana_210927a297.jpg)
![Closeup of Louisiana.](https://earthsciences.media.uconn.edu/wp-content/uploads/sites/3541/2022/10/16b_Louisiana_210927a300.jpg)
![Outline map of Louisiana.](https://earthsciences.media.uconn.edu/wp-content/uploads/sites/3541/2022/10/Louisiana-OutineUS.jpeg)
![Geo Map of Louisiana](https://earthsciences.media.uconn.edu/wp-content/uploads/sites/3541/2022/10/Louisiana-USGS-OFR-2005-1351.jpg)