First use of name; intent to name not stated, and no type locality designated. Is basal [member] of newly named Mineral Wells formation, uppermost formation of Strawn group (revised) in Brazos River Valley area, north-central TX on Bend arch. [Not recognized in Colorado River Valley, where Strawn is undifferentiated--beds of Drake (1893) are used there.] This coal bed, designated by Cummins (1891) as Coal Seam No. 1," apparently marks a change from the more typically marine sediments of the underlying Millsap formation (reinstated) of Strawn to the dominantly clastic, very shallow water, littoral deposits of the Mineral Wells formation. Since it is a stratigraphic horizon which is readily traced in the north TX area, it may be employed in the same manner as suggested by Cummins--as the line of division between the two major portions of the Strawn group in the Brazos River region. Conformably underlies Mingus shale [member] (new) of Mineral Wells. Thurber coal can be traced southwest to Thurber (Erath Co, Strawn basin) and northeast to the Cretaceous overlap. Correlation chart. Pennsylvanian age.

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