North Carolina, US

Paleontology and geology

The Precambrian: Most Precambrian sediments in North Carolina have been metamorphosed. The presence of a very rare and enigmatic Precambrian fossil, Pteridinium indicates that a sea was present over a portion of the state during the Late Precambrian. The Paleozoic: The Paleozoic is poorly represented by sedimentary rocks and fossils in North Carolina. Trace fossils called Skolithos have been found in some lightly metamorphosed Cambrian rocks. There is at least one other report of marine fossils from a quarry in south-central North Carolina, indicating that a shallow sea existed in the area at this time. The Late Paleozoic (Carboniferous and Permian) was a time of intense deformation, metamorphism, and mountain building, resulting in the rise of the Allegany Mountains. There are no sedimentary rocks or fossils from this time interval. The Mesozoic: The Mesozoic is represented by both marine and non-marine sedimentary deposits. During the Triassic, rift basins formed as a result of tectonic activity and lakes and rivers formed within these basins. Conifers and cycads grew along the lake margins; clams, crustaceans, and fish flourished in the aquatic environments; and various reptiles and mammal relatives roamed the area. There are no surface exposures of Jurassic rocks in North Carolina, but Cretaceous rocks show that the sea flooded North Carolina from time to time. Oysters and other molluscs flourished in the warm waters where sands, muds, and limy muds were being deposited. Dinosaurs roamed the shoreline. The Cenozoic: Erosion of the Appalachians continued into the Cenozoic and rivers carried the sediments to the Coastal Plain. During the Early Cenozoic, the sea repeatedly flooded eastern North Carolina and then retreated, producing sediments rich in marine life. The expansion and melting of continental glaciers caused sea levels to rise and fall repeatedly during the Quaternary. When sea level was high, sandy deposits accumulated, and fossils of molluscs, sea cows, sharks, and fish can be found in these sediments. Mastodons, horses, giant ground sloths, and smaller mammals flourished on land.