A Tragedy 35 Million Years in the Making

In his journals, Captain John Smith recalled his first impression of the Chesapeake Bay: “Heaven and earth never agreed better to frame a place for man’s habitation.” He was right about one thing. A celestial juncture had occurred there. 35 million years ago, a large asteroid or comet, called a bolide, smashed head-on into the continental shelf of ancient Virginia. Its remnants, a crater over 50 miles in diameter, lay hidden deep beneath the colony’s earliest European settlements at the mouth of the bay. Smith could not have known of this disaster, or that its consequences would haunt his adventures. Specifically, the bolide fueled an identical problem for early settlers and modern citizens alike: the Tidewater region’s bafflingly pitiful groundwater supply.

image00135 million years ago, Virginia was unrecognizable. High global sea levels pushed the Atlantic coastline west to roughly where Richmond sits today. A dense tropical rainforest blanketed the Appalachians. When the bolide hit, the impact likely incinerated all life forms within hundreds of miles and triggered massive tsunamis that washed over the Blue Ridge Mountains. According to geologist Wylie C. Poag, who discovered the crater and published his findings in 1998, the impact transformed Virginia’s coast into “a hellish cauldron of mass destruction.” The heat from the collision vaporized some of the seawater surrounding it, leaving only salt behind. This excess salt in turn was pushed into the groundwater, making it even saltier than the ocean itself.

Eventually the land recovered, life returned, and the crater was filled in by debris and water. The rivers of the region converged at the location directly above the crater’s topographical depression, which determined the eventual location of the bay. The hole, shaped like an upside-down sombrero, is completely invisible at surface level. Nevertheless, the ancient cataclysm continues to exact both good and harm.

w-oldBay_promoThe landscape that John Smith encountered, for example, was molded directly by the impact. As the explorer’s scouting party traveled northward and westward up the Bay’s rivers and tributaries, they found exposed cliffs, eroded by rapid sea level rise. This rise, up to 7.5 inches per century, is due to the coast literally slipping into the crater’s depression. The southern tributaries also cater to the whims of the crater. In contrast to surrounding rivers that flow naturally to the southeast, the York and James make sharp turns to the northeast, hugging the crater’s outer rim. This proved to be important in Smith’s decision to locate the first settlement at Jamestown, which was chosen for seclusion and defense.

Today, Jamestown is well-remembered as a paradigm of human suffering and privation. Between 1607 and 1625, sickness and starvation brought about an 80% mortality rate.  Some even resorted to cannibalism. Before scientific inquiry was applied to the study of the town, its early settlers were accused of being ill-prepared and naïve, completely at fault for the tragedy. They were tradesmen and merchants perhaps, but not farmers. Recently, researchers for Science magazine used dendrochronology to prove that an extreme drought had decimated Jamestown’s crops and water supply. They concluded that “even the best planned and supported colony would have been supremely challenged by the climatic conditions.”

georgepercy

No one yet, however, has taken a step further to analyze the effect the bolide may have had on the circumstances at Jamestown. The colonists should have had all the water they could ever need, regardless of drought, in the form of the robust James River. But this was not to be so. George Percy, who governed the colony through the “Starving Time” of 1609-1610, wrote that “our drinke cold water taken out of the River, which was at a floud very salt, at low tide full of slime and filth, which was the destruction of many of our men.” Other colonial accounts of life at Jamestown mention symptoms consistent with salt toxicity, such as lethargy and irritability. The problem was not the lack of water, but its atypical salinity.

Today, the James is still too salty to drink without expensive treatment. The reasons for the its high salinity are much more complex than what can be explained by proximity to the brackish Bay and the ocean itself. The bolide not only twisted the river to make it more susceptible to ocean flow, but also flushed Jamestown’s groundwater aquifer with excessively salty water generated during the impact.

bolideftmonroe

Saltwater aquifers, such as the one under Jamestown, had been observed in Virginia since the Civil War. In 1864, Union soldiers stationed at Fort Monroe attempted to drill a well but found its contents too salty to drink. Over the next five years residents at Fort Monroe kept drilling deeper, finally reaching a depth of 907 feet, but still inexplicably drew up saltwater. Neither the groundwater nor the James, which took a 90-degree turn to the northeast near the fort, were acting as they should.

The bolide’s disruption of Tidewater aquifers continues to cause extreme problems for water suppliers in the region. When modern wells are driven deep enough to penetrate the overlying sedimentary layers, only contaminated saltwater comes up. Endless political debates and lawsuits over drinking water in places such as Newport News, Poquoson, and Hampton Roads only exacerbate the challenges. With the recent rapid growth of these major urban and port centers, the available freshwater supply is near capacity, and the pressure for new sources has set planners in a frantic search for difficult alternatives.

We should treat the colonists of Jamestown better. A rock sent from “heaven” predestined them to a disadvantage of which they could have had no conception.. The similar struggles of both colonial and present-day Virginians with water show us why we should take caution when assigning blame or causality to certain historical events. The tragedy at Jamestown was 35 million years in the making. It will continue to reverberate through time. It is only by inviting scientific analysis into the human story that we can begin to understand and overcome its effects.

Cape-Charles-Southern-Tip

Sources

http://www.chesapeakebay.net/discover/bayecosystem/baygeology

College Of William And Mary, “Extreme Droughts Played Major Role In Tragedies At Jamestown, ‘Lost Colony,'” ScienceDaily, April 28, 1998.

Diane Tennant, “A Mystery, Meteor, and One Man’s Quest for Truth,” The Virginia-Pilot, June 24, 2001

http://meteor.pwnet.org/impact_event/impact_crater.htm

Kent Mountford, “Not all is well with overconsumption of water from aquifers,” Bay Journal, May 1, 2003.

http://smithtrail.net/the-chesapeake/formation/

United States Geological Survey, “The Chesapeake Bay Bolide Impact: A New View of Coastal Plain Evolution”

United States Geological Survey, “The Chesapeake Bay Bolide: Modern Consequences of an Ancient Cataclysm”

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