Neogene diatoms from Petersburg, Virginia

Sixty-two diatom taxa have been identified from a diatomaceous sandy clay that crops out near the outlet of Wilcox Lake, Petersburg. Virginia. These diatoms are mostly cosmopolitan marine forms, but some species suggest deposition in brackish water that had a freshwater inflow. The regional stratigraphy, as well as the pelecypods and foraminifers, indicates that the beds may have been laid down in a lagoonal or estuarine environment. The diatom assemblage suggests that the deposit is of early Pliocene age, although previous biostratigraphic studies have considered it to be latest Miocene.