Geologic map of the Fredericksburg 30' x 60' quadrangle, Virginia and Maryland
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Geology topics
Publications and source records attributed to Robert E. Weems.
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No abstract available.
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Paleocene vertebrate remains from the areas of Kingstree and St. Stephen, South Carolina, come from the Rhems and Williamsburg formations of the Black Mingo Group. Sedimentary textures and fossils indicate that both units accumulated in shallow, nearshore marine, lagoonal, and deltaic depositional environments. Calcareous nannofossils and dinoflagellates indicate that the vertebrate-bearing portions of the Williamsburg Formation near St. Stephen belong within calcareous nannoplankton Zones NP 3-5 (Lower Bridge Member) and within calcareous nannoplankton zones NP 8-9 (Chicora Member). Paleocene vertibrate remains from Kingstree probably all come from near the base of the Rhems Formation.
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Earthquake-induced liquefaction features (sand blows), found near Hollywood, S. C. , have yielded abundant clasts of humate-impregnated sand and sparse pieces of wood. Radiocarbon ages for the humate and wood provide sufficient control on the timing of the earthquakes that produced the sand blows to indicate that at least three prehistoric liquefaction-producing earthquakes (m//b approximately 5. 5 or larger) have occurred within the last 7,200 years. The youngest documented prehistoric earthquake occurred around 800 A. D. A few fractures filled with virtually unweathered sand, but no large sand blows, can be assigned confidently to the historic 1886 Charleston earthquake.
Multiple generations of earthquake-induced sand blows in Quaternary sediments and soils near Charleston, South Carolina, are evidence of recurrent moderate to large earthquakes in that area. The large 1886 earthquake, the only historic earthquake known to have produced sand blows at Charleston, probably caused the youngest observed blows. Older (late Quaternary) sand blows in the Charleston area indicate at least two prehistoric earthquakes with shaking severities comparable to the 1886 event.