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Fossil Content of Local Limestone

The fossil content of local limestone shows the diversity of life in the late Ordovician period. Bryozoans and brachiopods, nearly equal in abundance, form about 60 percent of the allochems in local limestone. Crinoids form about 20 percent and trilobites nearly 10 percent of the allochems.

The figure below shows pictures of fossils common to local bedrock.

Fossils common to local bedrock:  brachiopods and bryozoa

Fossils common to local bedrock:  trilobites, gastropods, coral, and mollusk.

According to detailed studies by Martin (1975), brachiopods and trilobites decrease appreciably in abundance upward in the Cincinnatian Series. In contrast, algae, ostrocodes, and corals, which are uncommon throughout most of the sequence, are very common in the upper part. Dolomite forms less than 1 percent of the limestones of the lower part of the sequence, but more than 5 percent of those in the upper part.

The figure below shows photomicrographs of local limestone samples bearing several types of invertebrate fossils.



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Last Updated: September 16, 2010
Designed by Capstone Students in the Bachelor of Arts in Technical and Scientific Communication