The Aquia Formation is a geologic sandstone formation that extends from the upper Chesapeake Bay to the James River near Hopewell, Virginia. It consists of clayey, silty, very shelly, glauconitic sand. Fossil records indicate that this stratigraphic unit was created during the Paleocene. The Aquia formation was named for Aquia Creek where it is exposed in cliff faces along the banks.

Geology

Lithology

When uncovered, it appears dark green to gray-green, argillaceous, with well sorted fine- to medium-grained sand and locally indurated shell beds. It is between 0 and 100 feet thick in Maryland. Quartz and phosphatic pebbles and/or very coarse glauconitic quartz sand mark the base of the unit. A few hard streaks of shells or thin "rock" layers are often reported but appear to be more abundant in the sections south of the James River.

Stratigraphy

The Aquia formation is overlain by the Nanjemoy Formation and overlies the Brightseat Formation. The Aquia formation is broken down into two members: the lower Piscataway member and upper Paspotansa member.

Age

The Aquia Formation is thought to be 59.0-55.5 million years old. The Piscataway member is 59–56.25 million years old, and the Paspotansa member is 56–55.5 million years old. This is the Paleocene period. Older publications describe the Aquia as being of Eocene age.

Fossils

Vertebrates

Bony fish

Chondrichthyes

Sharks

Rays

Reptiles

Crocodylians

Turtles

Mammals

Mammal fossils are extremely rare.

Birds

Bird fossils are extremely rare.

Molluscs

Gastropods

Bivalves

Cephalopods