Is one of eight formations of Interlake Group. Name extended in subsurface from southern CN into the central Williston basin of ND where it consists of dolomite that may be barren to rich in skeletal marine fossils. Considered to be a thick sequence [but total thickness in report area not stated.] Fossils include massive, tubular, branching and bulbous stromatoporoids, solitary and colonial rugose corals, crinoids, bryozoans, brachiopods, mollusks. Dolomitization has masked the structure of many of the fossils. Bedding features include lamination, contortion, bioturbation, current bedding, and accretionary reef fabric. Overlies Guernsey Formation (extended into the basin from CN). Upper contact revised in that Cedar Lake is overlain by the newly named Grondale Formation of Interlake Group. History of stratigraphic nomenclature chart. Silurian age.

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