DISCOVERY OF SHOCKED QUARTZ, STISHOVITE NANO PARTICLES, AND FRACTURED SILICA-GLASS MICRO-FIBERS ATTRIBUTABLE TO THE JETTING PHASE OF THE 35.4-MA CHESAPEAKE-BAY ASTEROID IMPACT

In 1995 an 85-km-diameter, 35.4-million-year-old impact crater was reported by the U.S. Geological Survey below the lower Chesapeake Bay (CB). However, the universally agreed ~2,000 km³ of material ejected landward by the impact have gone unrecognized by geologists concerned with U.S. Mid-Atlantic Coastal Plain. Thus the “upland deposits,” forming a semicircle ≥100 km landward of the crater center have been ascribed exclusively to geologic processes known prior to the crater’s discovery. After centuries of debate these strange facies were claimed to be the work of rivers, following the work of Schlee (1957), who stated “The upland deposits occur mainly on the coastal plain where they form a plateau cap” … leading to a paradox. Those deposits are typically 5 to 10 meters deep and consist mainly of compacted “quartz silt.” Surely rivers cannot flow on plateaus, let alone emplace deep silt deposits over a ~100-mile-long clay plateau sloping (toward the crater center) at a mere 0.56 m/km (data from the USGS).

The first author of this submission has for two decades studied all facets of impact geology, both theoretic and in the field, and he alone collected soil samples from three geologically differing locations near Alexandra, Virginia, ~200 km from the CB crater center. Each of his co-authors is a top-notch materials scientist with one or more speciality differing from the others. We found in each of the three sampled locals evidence of shocked quartz, nano-particles of stishovite, and tiny silica glass fibers shown by IR to contain large amounts of water! A titanium-rich silica glass recorded by ESR is also attributed to those fibers. Natural silica glass (not created by lightning) and stishovite are both universally accepted as evidence of impact origin. Thus, given the results of the experiments I will present here, we are able to deduce that our samples are the never-before-reported products of “jetting-phase” ejecta, wherein the first touch of an asteroid impacting at a 25° – 45° angle to the Earth’s surface instantly vaporizes and accelerates the debris at low angles northward nearly twice as fast as the impactor (H J Melosh, Oxford Press, 1987, p. 50). Therefore, our glassy fibers must have re-condensed into solids while in ballistic flight. We believe that these discoveries constitute a major advance in the field of impact geology.