General Meeting September 9, 2001
Scott Bruce
Geologist and Environmental Program Planner
for the Virginia Department of Environmental Quality,
Ground Water Withdrawal Program.

Scott Bruce has been in a geologist for the last 10 years. He is a 1983 graduate of Virginia Tech. He has over 18 years experience in environmental compliance and earth science publishing for state and federal agencies. He has written numerous research articles and has conducted many professional presentations. He is a co-recipient of the Thomas Jefferson Award for Outstanding contributions to Natural Science.

Thirty-five million years ago a "bolide", a meteor or comet, one mile wide hit the earth and created a crater 56 miles in diameter (as big as the Grand Canyon). It is the sixth largest crater known to be on the earth's surface. The bolide hit the ocean at 60,000 mph and vaporized on impact. Landing in about 600 feet of water, it probably created a tidal wave 600 feet high that traveled as far as 200 miles inland. The crater is one mile deep and it has seven miles of fractures beneath. The crater has an inner diameter of 25 miles, an outer diameter of 56 miles, and 85 miles of disruption boundary. The crater is filled with "breccia", mixed up layers of sediment. Nine layers of sediments were tossed and resettled.

The level of the ocean has risen and fallen over time. The land from Route 95 eastward has been underwater and exposed all the way to the continental shelf. The Eastern Shore of Virginia is essentially a large sand bar, recent in earth history. Cape Charles sits on top of "ground zero" and the parts of Route 17 in York County rise in elevation outlining rim of the crater. A aerial photograph shows how the rivers of the Chesapeake Bay to curve toward the center of the crater-- the Elizabeth and York River turn sharply at their mouths.

The crater was discovered and confirmed over the last 60 years. In the 1940s, there was a severe draught and one geologist, after finding mixed layers of sediment while drilling for water resources, hypothesized the existence of the crater. In 1983, a geologist doing deep sea drilling found evidence of impact from bolides. 'Shocked quartz' and 'tektite glass' are created only from extreme impact such as meteors or nuclear testing and these were found in core samples from beneath the ocean floor.

When Scott was new to his job in 1983, he found core samples in Eastern Virginia that appeared to have fossil layers mixed up. When the core samples were sent away to be analyzed, he was accused of mixing up the layers because the formaninifera (microscopic plant life) was out of chronological sequence. In 1986, Scott's colleague, David Powers, recognized mixed samples when drilling in Exmore, VA. In 1990, at Kiptopeke and in Newport News more mixed 'forams' but similar core samples were found while drilling for water resources. In 1993, oil finding/drilling rigs found mixed core samples and unusual seismic readings indicating disruption to the earth's crust.

There are six or more aquifers below Eastern Virginia that vary in 'chlorinity'. Chlorine, the geologists' measure of water quality, contributes to salinity. 'Brackish' water is often not as salty as the ocean; 'brine' is water quality saltier than the ocean. Only a few wells in the area, one in Kiptopeke, are brine. Only the top level of underground water is affected by rainfall. Aquifer water levels are usually affected by pressure. A well is like a straw and it lets the pressure out. The more wells, the lower the water level.

Ground water resources have probably been affected by the impact crater. The contours underlying the land are pushed back into the continent. The water in the aquifers is more brackish than should be expected and this may be due to excessive 'differential flushing'. Sea water is being flushed in more frequently due to the fractured and bent contours of the earth's crust.

Scott and his colleagues continuously monitor water quality and test water at 250 wells each quarter. The actual levels of chlorinity do not match the scientific model of differential flushing. The chlorinity levels may be a result of the crater or other forces we do not yet understand.