During the late Eocene, the formerly quiescent geological regime of the Virginia Coastal Plain was dramatically transformed when a bolide struck in the vicinity of the Delmarva Peninsula, and produced the following principal consequences:
- The bolide carved a roughly circular crater twice the size of the state of Rhode Island (~6400 km2), and nearly as deep as the Grand Canyon (1.3 km deep).
- The excavation truncated all existing ground water aquifers in the impact area by gouging ~4300 km3 of rock from the upper lithosphere, including Proterozoic and Paleozoic crystalline basement rocks and Middle Jurassic to upper Eocene sedimentary rocks.
- A structural and topographic low formed over the crater.
- The impact crater may have predetermined the present-day location of Chesapeake Bay.
- A porous breccia lens, 600-1200 m thick, replaced local aquifers, resulting in ground water ~1.5 times saltier than normal sea water.
- Long-term differential compaction and subsidence of the breccia lens spawned extensive fault systems in the area, which are potential hazards for local population centers in the Chesapeake Bay area.
