Named for Point Augusta. Type locality designated as exposures in nearly continuous cliffs that extend west from Point Augusta along Icy Strait to Whitestone Harbor and south from point along Chatham Strait to False Bay, Chichagof Island, southeastern AK. Consists of interbedded thin-bedded graywacke and dark gray argillite with conglomerate, siltstone and thin-bedded light-gray limestone. Is probably at least 5000 ft thick. Unconformably(?) underlies Kennel Creek Limestone of Silurian and (or) Devonian age. Is oldest unit in stratigraphic section for Chichagof, Baranof, and Kruzof Islands. Age is considered to be Late(?) Silurian on basis of lithostratigraphic correlation with fossiliferous rock to north in Chilkat Range.

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