Silicified mudstone, Accomack County, Virginia.
Outcroppings of silicified mudstone occur off the Atlantic coast of Accomack and Northampton counties in Virginia. Silicified mudstone seems to be associated with offshore Pliocene-age Yorktown or Omar formation estuarine deposits.
Silicified mudstone can occur as large sheets, irregular nodules, tube-like marine animal burrows, internal molds of articulated mollusks, and blocky section with dense shell material. Fossils embedded in the mudstone include crabs, mud-shrimp, oysters, clams, and a variant of extant species. High quality forms of silicified mudstone are fine-grained, have a conchoidal fracture, and retain a sharp cutting edge. Lesser quality types are grainy with inclusions and irregularities.
Eastern shore of Virginia.
Late Archaic period points have been identified made from silicified mudstone. Further use of this material can not be accurately assessed.
Prepared By Egloff 2008