Cyclic change in late triassic lacustrine communities.

A new type of lake and shore assemblage has been found in the Late Triassic age rocks of North Carolina and Virginia (Dan River group). It includes abundant aquatic reptiles, fishes, at least seven orders of insects, crustaceans, and a diverse flora. Cyclic changes in the fauna and flora correlate with sedimentary cycles, which together reflect the repetitive development and extinction of large meromictic lakes.