Amherstburg dolomite (new name) is a magnesian calcarenite, 0 to 30 feet thick. Included in Upper Monroe [Detroit River dolomite]. Underlies "Lucas" dolomite and overlies Anderdon coral limestone. Named for fact that it forms bottom of eastern channel of Detroit River, opposite Amherstburg, Ontario. Also exposed in Sylvania district, OH.

Source: GNU records (USGS DDS-6; Reston GNULEX).

Amherstburg formation of Detroit River group revised to include Sylvania sandstone, where present, as basal sandstone member of formation. Includes Filer Sandstone lentil (new). Except for Sylvania and Filer sandstones, Amherstburg is limestone or dolomite. The only evaporites within the formation are occasional nodules of anhydrite observed in cores from wells drilled in the basin. Beds assigned to Amherstburg in central part of basin agree with fauna, stratigraphic position, and lithologic character of Amherstburg at its type locality. Noncherty limestone or dolomite beneath evaporites and above the Bois Blanc formation on north flank of Michigan basin, and heretofore described by the writer [Landes, 1945] as upper part of the Bois Blanc, is now considered to be Amherstburg. Basal formation of Detroit River group. Underlies Lucas formation. Overlies Bois Blanc formation. Age is Middle Devonian.

Source: GNU records (USGS DDS-6; Reston GNULEX).