Geologic Division ----
Coastal and Marine Geology ----
Woods Hole Field Center
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Up: Chesapeake Bay Bolide
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
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
A structural and topographic low formed over the
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.
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Last Modified: 4/1/98