Beds of the Comanche Series. 11 



entirely distinct from each other in paleontologic characters, and 

 that it could be appropriately made into two divisions. For 

 the upper of these, which is composed of the Caprina limestone' 

 and the " Comanche Peak Group " of Shumard in part, the 

 name Fredericksburg was retained, and to the lower the name 

 Trinity Division was given, thus dividing the Comanche Series, 

 more in accord with its natural grouping, into three great divis- 

 ions, instead of two, as originally proposed. 



Since the publication of his Arkansas report* the writer has 

 do voted several years to the study of the Trinity Division 'in 

 Texas and Indian Territory, and has more fully differentiated 

 its beds from those of the overlying Fredericksburg Division, 

 and, furthermore, ascertained that it constitutes a paleontologic 

 and stratigraphic division of the utmost importance in the inter- 

 pretation of the North American Cretaceous. 



In the same report upon the Arkansas Cretaceous a prelim- 

 inary description of the Trinity Division was made, separating 

 it into a lower or arenaceous terrane, and an upper or calcareous 

 terrane, for which, in a final paperf upon the stratigraphic sub- 

 divisions of the Comanche Series, read before the Geological 

 Society of America -at its Washington meeting, December, 1890, 

 the names of the Trinity sands and Glen Rose beds were re- 

 spectively proposed and the following general arrangement of 

 the series given : 



C. The Washita or Indian Territory Division. 

 10. The Denison beds. 



9. The Fort Worth limestone. 



8. The Duck Creek chalk. 



7. The Kiamitia clays or Schloenbachia beds. 

 B. The Fredericksburg or Comanche Peak Division. 



6. The Caprina and Goodland limestone. 



5. The Comanche Peak chalk. 



4. The Gryphxa rock and Walnut clays. 



3. The Paluxy sands. 

 A. The Trinity Division. 



2. The Glen Rose, or alternating, beds. 



1. The Trinity, or basal, sands. 



* The Neozoic Geology of Southwestern Arkansas, vol. n of the Annual 

 Report, Geological Survey of Arkansas, 1888. 

 f Loc. cit. 



