First use of name; intent to name not stated, and no type locality designated. Area of report is Lake Valley region, Sierra Co, NM in Orogrande basin. Is about 100 ft thick in section at Lake Valley. This bed of argillaceous black shales appears to form the base of the Devonian section of the region. Thus far it has proved to be nonfossiliferous. Its age is deduced from its stratigraphic position; it is believed to be the eastward extension of a similar black shale found near Silver City, Grant Co, NM in Basin-and-Range province, which has been called Silver shales--that name is here retained. Overlies with marked erosional unconformity the Silurian Santa Rita limestone (new); is overlain by Bella shales (new). Is of Devonian age. Cross section, geologic section.

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