The Dulles Compartment

Dulles International Airport rests on top of a large subsurface ground water compartment. It is bounded on the north by a prominent dike exposed along Virginia route 606 (Old Ox Road) in the vicinity of the Dulles Greenway, bounded on the south by the Centreville diabase lopolith, and bounded on the west by the irregular diabase body beneath the western margins of the airport property, in combination with a swarm of N-S aligned diabase dikes. It is also largely bounded to the east by the western margins of the Herndon diabase lopolith. Contained within, is a large expanse of Balls Bluff siltstone and it's thermally-metamorphosed remnants near the diabase contacts. The inferred systematic closure of the Balls Bluff siltstone fractures with depth (due to progressive increases in the horizontal component of confining pressure) is believed to effectively 'floor' the compartment. The fluids within the compartment are thought, strictly however, to be partially compartmentalized, since just east of the airport a small subsurface opening near the Herndon lopolith occurs.  We refer to this portion of the Culpeper basin as the "Dulles compartment".

|| Culpeper Basin AMT || USGS - Eastern Earth Surface Processes Team || USGS - Geology || USGS ||

Contact: Herbert A. Pierce
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