The Geology of Texas - Volume 1

The Harpersville formation, resting upon the Thrifty, consists of a sandstone at the base, followed by shales, including coal beds and some limestones and sandstones.  The coal beds mined at Newcastle are in this formation.  North of Young  County the limestones of the formation give place to sandstones.  In the Brazos River valley the following members are recognized: sandstone and shale; Crystal Falls limestone; shale, sandstone, limestone, and coal beds; Belknap limestone; shale, and sandstone; and Saddle Creek limestone.  The fauna of the Saddle Creek limestone is believed by Roth to be equivalent to that of the Neva limestone of Oklahoma and Kansas although the genus Schwagerina was not found in the Saddle Creek limestone (1353b).  Some of the limestones of this formation continue northward through Jack County, but are replaced in Montague County by sandstones and shales.   Type locality:  The type locality is at Harpersville in Stephens County; thickness, 240 t o300 feet.