About 35 million years ago, a large comet or meteorite slammed into the western Atlantic Ocean on a shallow shelf, creating the Chesapeake Bay impact crater. The crater is now covered by Virginia's central to outer Coastal Plain sediments and

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After six year intensive exploration for high-grade hematite deposits, the channel iron deposits (CIDs) were included as a specific iron ore target in the Hamersley Province iron ore exploration programme in 2000. The exploration model was simple and was based on the then current understanding of CID genesis. Fundamental to the model was an interpretation that CIDs could be entirely concealed in their channels after their final accumulation stage. Inversion to mesas and therefore exposure of the CID profile would only occur in areas where the modern drainages follow the ancient drainages, and have significantly incised their current bedrock. After a number of partially successful attempts, exploratory drilling in 2002 in the Caliwingina valley in the northern Hamersley Range identified significant CID mineralisation. Subsequent drilling programmes from 2003 onwards revealed the presence of a large CID system which stretches from the middle reaches of the Caliwingina Creek to deep under the sediments of the Fortescue Valley, a channel length of more than 30 km. Geological resource estimation suggests that Caliwingina is presently the third largest CID system of the Pilbara (after Yandicoogina and Bungaroo) and is of comparable size to the pre-mining Robe River system (1?6 Bt), with comparable Fe-grades to the Yandicoogina global resource grade (57?7%Fe). Large detrital iron and canga deposits overlie the Caliwingina CID, or interfinger with it, and although the economics of these are presently unfavourable, they could ultimately present a low-grade iron resource of slightly smaller size to the CID mineralisation at Caliwingina. Together with the recently discovered Serenity and Solomon deposits and other smaller occurrences, the Caliwingina deposit is part of a major new CID district in the central Hamersley Ranges, approximately halfway between Yandicoogina and Robe River. Although exploration in this new district is still underway, the preliminary indications are that this area will provide a total CID resource well over 3 billion tonnes and a detrital iron resource of similar size and is on a par with the major known CID systems in the Hamersley Province.

This report presents an operational summary for the drilling of a deep scientific corehole at the National Aeronautics and Space Administration's (NASA) Langley Research Center, located at Hampton, Virginia. This corehole is an important research activity of the Chesapeake Bay Impact Crater Project. This project is a multi-agency effort to understand the formative processes, the physical distribution and characteristics, the geologic history, and the hydrologic implications of the Chesapeake Bay impact crater, a major subsurface geologic structure. The Langley corehole is located in the Atlantic Coastal Plain within the boundaries of the buried Chesapeake Bay impact structure. Drilling operations by the USGS began at the Langley Center on July 22, 2000, and were essentially completed with the removal of the drill rig from the work site on October 13, 2000. The borehole was continuously cored to a total depth of 2,083.8 ft, and suites of geophysical logs were run in the hole on three occasions. The corehole penetrated the entire section of materials that fills the impact structure (1,280.4 ft), as well as overlying post-impact Cenozoic sediments (774.3 ft) and a short section of crystalline rocks (29.1 ft) beneath the crater fill. Appendix A of this report lists the main participants in the drilling operations at the Langley Center. Appendix B lists the dates, times, and core-recovery information for the coring runs conducted in the Langley corehole.

Virginia needs a reliable water supply to sustain its growing population and expanding economy. In 1990, the aquifers in the Coastal Plain supplied about 100 million gallons per day (mgd) to the citizens, businesses, and industries of Virginia.