Geology & Fossils
Fossils are rare in the Blue Ridge Mountains, where rocks are largely metamorphic and igneous. In the Piedmont is the Carolina Slate Belt, which stretches from southern Virginia across the Carolinas into central Georgia. In South Carolina, this region harbors fossils of trilobites that are much younger than North Carolina’s Eocambrian sea pen. Yet they still lived more than half a billion years ago, during the Cambrian Period!
Mesozoic basins are found in the eastern Piedmont along the Atlantic Coast. They were formed when North America pulled away from Europe and Africa after the Appalachians were formed. Spectacular dinosaur footprints and bones of diverse creatures have been found in some of these basins. Unfortunately, the basin that South Carolina shares with North Carolina has not produced such fossils.
Many rocks from the Triassic and Jurassic periods — when the Mesozoic basins were formed — lie under the Coastal Plain. Much oil has been pumped from these rocks. North America’s first coal mine produced Triassic and Jurassic coal from just west of Richmond. These fossil fuels tell us that the sea rose and fell during the early Mesozoic Era. Marine animals left us oil, while lush forest that grew on land produced coal.
The Jurassic Period was followed by the Cretaceous Period. This was the last period of the Mesozoic Era, which ended about 65 million years ago. As in North Carolina, Cretaceous fossils can be found near the surface of the Coastal Plain.
But most Coastal Plain fossils represent animals that lived during the Cenozoic Era. Fossils of marine invertebrates, sharks, and bony fishes are common in both Mesozoic and Cenozoic rocks. Scattered dinosaur fossils are rare and don’t always prove the land was dry at the time. For rivers and floods sometimes washed dinosaurs out to sea, where their bones sank. Thus, it is not unusual to find a dinosaur bone amidst clams. Fossils of Cenozoic vertebrates that lived on land include horses, elephants, and birds.
South Carolina’s Coastal Plain fossils tell us of a sea that can’t make up its mind. Most Paleocene, Eocene, Oligocene, and Miocene fossils are of marine animals. Younger Pliocene and Pleistocene fossils represent both marine and land animals. Late Pleistocene fossils are mostly marine, as the sea rose again with the melting of the great Ice Age glaciers.