316 R. T. HILL — GEOLOGY OF RED RIVER. 



WASHITA DIVISION OF THE COMANCHE SERIES. 



Relation to other Divisions. — As an example of this differentiation away 

 from this shoreline let us take the beds of the Washita division of the 

 Comanche series. The Washita division is the uppermost of the three 

 grand divisions of the Comanche series, and is essentially composed of 

 the shallowing beds which followed the culmination of the great subsi- 

 dence during the Comanche time, as represented in the chalkier beds of 

 the Fredericksburg division. The term " division," which has the 

 equivalency of the word " group " as used by Dr White for the Upper 

 Cretaceous, was first applied by me * to the beds of the Comanche series 

 for the purpose of conveniently grouping them until their subdivisions 

 could be more minutely studied and classified. Fossils from beds which 

 are now recognized as the upper portion of the Comanche series had 

 been originally collected in the vicinity of fort Washita, in Indian Terri- 

 tory and in nprthern Texas by Dr G. G. Shumard f and Professor Jules 

 Marcou,t and Dr B. F. Shumard had named certain of these beds the 

 Washita limestone ;§ hence the upper division was called the Washita 

 division, and in a similar manner, from the fact that the fossils described 

 by Dr Roemer from Fredericksburg. Texas, and by Dr Shumard from 

 Comanche peak were discovered to belong to beds of the middle division, 

 the lower part of the series has been called the Fredericksburg or Co- 

 manche peak division. 



In my earlier writings the Trinity division, including the Trinity 

 sands and the great development of alternating lime beds of the Glen 

 Rose, was not separated from the Fredericksburg division, nor had these 

 lower beds been recognized or intimated by previous writers. A fuller 

 definition of the Trinity division has recently been published by the 

 writer. 1 1 



The necessity for this arrangement into divisions will be furthermore 

 appreciated by the accompanying table, which shows the progressive 

 evolution of knowledge concerning the Cretaceous formations of Texas, 

 and is my final classification of their succession and nomenclature. 

 Some of the beds may be subdivided again in the future. 



The Fredericksburg culminates everywhere throughout its extent in 

 very chalky limestones which, in central Texas, have been denominated 

 Caprina hmestone and the Comanche peak beds by Shumard ;^f and its 

 northern attenuated portion in Indian Territory and northern Texas 



* Am. Jour. Sci., April, 1887. 



t Exploration of the Hed river of Louisiana, eto, 1852. 



t Geology of North America and other works. 



g Trans. St. Louis Acad. Sci., vol. i, 1860, p. 586. 



II Proe. of the Biological Soe. of Washington, June, 1893. 



% Trans. St. Louis Acad, of Sci., 1860. 



