40 RAYMOND C. MOORE AND FREDERICK B. PLUMMER 



The fourth formation of the Cisco, the Pueblo, is named from a 

 town on the Missouri, Kansas & Texas Railway in northeastern 

 Callahan County, where the rocks of this division are typically 

 exposed. It lies conformably upon the Harpersville formation and 

 includes the strata to the top of the persistent Camp Colorado 

 limestone which forms a readily traceable escarpment both in the 

 Colorado and Brazos valleys. The thickness of the formation, 

 which averages from 150 to 200 feet, is largely made up of gray, 

 buff, or reddish shale. The limestone beds at the top are thin, 

 3 to 6 feet, but are remarkably uniform and persistent. The fauna 

 of the Pueblo is similar to that of the subjacent Harpersville and 

 is typical of the uppermost Pennsylvanian. 



The strata above the Pueblo belong to the Moran formation 

 which is defined to include the shale and limestone to the top of 

 the persistent yellow limestones which outcrop typically in the 

 vicinity of Moran, Shackleford County, and in the Moran oil field. 

 These limestones, commonly three in number, are closely associated 

 and are grouped together as the Sedwick member. The Sedwick 

 beds are distinguished by widely distributed and abundant small 

 sUicified fossil casts, mainly gastropods. The Sedwick may be 

 identified with little difficulty by reason of this peculiarity of the 

 contained fossils, the lithologic character of the limestones, and the 

 stratigraphic position. The average thickness of the formation is 

 150 feet in the south and 200 feet or more in the north. 



The uppermost division of the Cisco group is named the Putnam 

 formation, from a town in Callahan County. It includes the shale 

 and limestone overlying conformably the Moran formation to the 

 top of the Coleman Junction limestone of Drake which comprises 

 the upper member of the formation. The shale which follows the 

 Coleman Junction bed contains fossils which appear to belong to 

 the Lower Permian, but those which have been found in the lime- 

 stone are not dissimilar from those in the subjacent divisions of the 

 Cisco. As in Kansas, there appears to be here a gradual transition 

 from the Pennsylvanian to the Permian, and a line of division is 

 more or less arbitrary. The Coleman Junction limestone has been 

 selected as a conspicuous, readily traceable line of such division, 

 but it is possible that future detailed investigations will show the 

 presence of Permian species below this horizon. The thickness of 



