TypeFormation OtherSchist Thickness168 m UnderliesTomstown Dolomite PrimarySandstone, Quartzite
OverliesHarpers Formation CountryUnited States Named forAntietam Creek Unit ofChilhowee Group
RegionWest Virginia, Pennsylvania, Maryland
The Antietam Formation or Antietam Sandstone is a geologic formation in Pennsylvania, Maryland and West Virginia. It is largely quartz sandstone with some quartzite and quartz schist. It preserves Skolithos trace fossils dating back to the Cambrian Period.