Formation and aftermath
During the warm late
sea levels were high, and the
Tidewater region of Virginia lay in the
coastal shallows. The shore of eastern
North America, about where
Richmond, Virginia, is today, was covered with dense
tropical rainforest, and the waters of the gently sloping
continental shelf were rich with marine life that was depositing dense layers of
lime from their microscopic
The bolide made impact at a speed of many kilometers per second, punching a deep hole through the sediments and into the
basement rock. The bolide itself was completely vaporized, with the basement rock being fractured to depths of 8 km (5.0 mi), and a
peak ring being raised around it. The deep crater, 38 km (24 mi) across, is surrounded by a flat-floored terrace-like ring trough with an outer edge of collapsed blocks forming ring faults.
The entire circular crater is about 85 km (53 mi) in diameter and 1.3 km (0.81 mi) deep, an area twice the size of
Rhode Island, and nearly as deep as the
Grand Canyon. However, numerical modeling techniques by Collins et al. indicate that the post-impact diameter was likely to have been around 40 km (25 mi), rather than the observed 85 km (53 mi).
The surrounding region suffered massive devastation.
David Powars, one of the impact crater's discoverers, has described the immediate aftermath: "Within minutes, millions of tons of water, sediment, and shattered rock were cast high into the
atmosphere for hundreds of miles along the East Coast." An enormous
tsunami engulfed the land and possibly even reached the
Blue Ridge Mountains.
 The sedimentary walls of the crater progressively slumped in, widened the crater, and formed a layer of huge blocks on the floor of the ring-like trough. The slump blocks were then covered with the rubble or
breccia. The entire bolide event, from initial impact to the termination of breccia deposition, lasted only a few hours or days. In the perspective of geological time, the 1.2 km (0.75 mi) breccia is an instantaneous deposit. The crater was then buried by additional sedimentary beds that have accumulated during the 35 million years following the impact.
The impact has been identified as the source of the
North American tektite field, namely the