The shore of eastern North America, about where Richmond, Virginia is today, was covered with thick 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 shells.

[citation needed] The bolide made impact at a speed of approximately 17.8 kilometers per second (11.1 miles per second),[4] punching a deep hole through the sediments and into the granite continental basement rock.

USGS scientist David Powars, one of the impact crater's discoverers, 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."

The impact crater created a long-lasting topographic depression which helped predetermine the course of local rivers and the eventual location of the Chesapeake Bay.

The present freshwater aquifers lie above a deep salty brine, remnants of 100- to 145-million-year-old Early Cretaceous North Atlantic seawater, making the entire lower Chesapeake Bay area susceptible to groundwater contamination.