Paleontology and geology
Warm shallow seas covered the continental shelf in the southern and eastern parts of the state during the Ordovician and limy sediment was deposited. Tectonically, the region remained quiet. The water deepened to the northwest into an ocean basin. On the slope and in the basin, dark shale rich in the remains of plankton accumulated. In the shallow water, reef communities of sponges, crinoids, brachiopods, bryozoans, and nautiloids flourished. In deeper water, graptolites and other plankton floated near the surface.