Dark-gray to white, thin- to thick-bedded, fine- to medium-grained marble that is locally dolomitic, intercalated with greenstone and greenschist of the Gambier Bay Formation (S.M. Karl, unpub. data). On Admiralty Island, Lathram and others (1965) reported Middle Devonian(?) corals from the Gambier Bay Formation, but suggested that rocks older than Devonian may be included in the unit. On Kupreanof Island a possibly equivalent unit of schist and marble contains Silurian or Devonian crinoid, conodont, stromatoporoid, and rugose coral fossils, but age-diagnostic fossils suggested an age of Emsian (late Early Devonian) to Famennian (Late Devonian) (Karl and others, 1999). A Triassic age was inferred for this unit by Kelley (1990b), but the fossil of that age was most likely from the Triassic Hyd Group (unit ^hg). A probable correlation is with the limestone of map unit Dlse, which consists of the Wadleigh, Black Cap, and similar limestone units