PENNSYLVANIAN STRATIGRAPHY OF TEXAS 41 



the Putnam formation is 125 to 150 feet in the Colorado Valley, 

 and about 175 feet in the Brazos Valley. 



The middle and upper portions of the Cisco, that is, the Thrifty 

 formation and succeeding divisions, correspond in stratigraphic 

 position and faunal character with the upper part of the Kansas 

 section included in the Lansing to Wabaunsee formations. The 

 Texas divisions cannot be correlated precisely on the basis of 

 information at hand with the Kansas formations, but there can be 

 no doubt as to their essential equivalence. 



PHYSICAL HISTORY OF THE TEXAS PENNSYLVANIAN 



Sedimentation began in the north Texas area in Pottsville time, 

 the sea first advancing into the region probably in the very early 

 Pottsville. Black shale and later a thick mass of limestone were 

 widely deposited about and over the Llano region and northward 

 probably beyond the Red River. The sea of this time was evi- 

 dently an invasion from the southwest, and the faunas represent 

 the earliest typical marine Pennsylvanian of the continent. The 

 epoch closed with more deposition of carbonaceous muds. 



At the end of Bend time the sea withdrew temporarily from the 

 Llano region and probably from most of the north Texas area. 

 However, there was little erosion of the soft Smithwick shale, and 

 the unconformity which, is observed at the base of the Strawn is 

 defined mainly by the difference in strike of the younger beds, the 

 conglomerates and very remarkable change in the character of the 

 sediments, and the overlap of the Strawn upon the Bend. The 

 ancient land to the east representing the northeast part of Columbia, 

 or, [as it has been termed recently, Llanoria,^ was notably upKfted 

 and furnished a very great amount of clastic debris to the shallow 

 sea lying to the west. This was spread out in irregular lenses with 

 a general delta structure, dipping westward and younger deposits 

 overlapping the older. Coal was deposited locally. The fauna had 

 undergone a marked change from that of Bend time and at least in 

 the upper part of the Strawn was very closely related to the southern 

 Oklahoma Wewoka fauna. This portion, and perhaps all of the 

 Strawn, is referable to Allegheny time. 



^ H. D. Miser, paper presented before the Geological Society of America, Decem- 

 ber, 1920. 



