48 ENVIRONMENT OF VERTEBRATE LIFE, ETC. 



Second, the upper Pennsylvanian and Permo-Carboniferous outcrops of 

 the central and western portion of the United States east of the Front 

 Ranges of the Rocky Mountains, defined in PubHcation 207 of the Carnegie 

 Institution as the Plains Province. 



Third, the upper Pennsylvanian and Permo-Carboniferous outcrops west of 

 the Front Ranges of the Rocky Mountains, and possibly extending into British 

 Columbia and Alaska, defined in Publication 207 as the Basin Province. 



Between the first and second areas lie the uplift of southern Missouri 

 and the regions directly north and south of it, which are now largely devoid 

 of post-Mississippian deposits and probably never had any considerable 

 amount of such deposits. 



Between the second and third areas lie the outcrops of pre-Pennsylvanian 

 rocks of the crests of the Rocky Mountain Front Ranges. It is not im- 

 possible that connection was established between these areas either at the 

 north or the south end, or both ends, of the barrier, but the separation was 

 sufficient, and sufficiently long sustained, to determine the deposition of very 

 different material and the location of very different faunae on the two sides, 

 as is shown elsewhere in this work. 



In describing the three provinces, the author has reduced the amount 

 of descriptive material and the amount of quotations to a minimum con- 

 sistent with an attempt to place the conditions before the reader. Much 

 of the material is readily available in the reports of the geological surveys 

 of the United States, Canada, and the various States, and excellent bibliog- 

 raphies will introduce the student to a very extensive literature. Older 

 publications, whose value is largely historical, have been sparingly mentioned 

 in the discussion, though a large number have been carefully considered for 

 the many side lights which have borne such an important part in the prepara- 

 tion of the argument. In general, only the later papers which have sum- 

 marized the evidence are quoted or discussed. Frequent references have 

 been made to Publication 207 of the Carnegie Institution, where a part of 

 the material has been presented, and its repetition seemed needless. 



The accompanying correlation tables show the relation of the beds in 

 the different provinces. It does not purport to be a statement of exact 

 equivalence, but to show the general relation of the beds within limits 

 sufficiently exact to support the thesis of this paper — that the conditions of 

 red-bed deposition appeared at progressively higher levels from east to west. 

 As is evident, the Pennsylvania and West Virginia sections have been taken 

 as the standard for the Eastern Province and the Kansas section for the 

 Western Province. The breaks between various areas render the exact cor- 

 relation difficult and perhaps impossible, but are not beyond the possibility 

 of bridging within usable limits. The main breaks in the Eastern Province 

 are between the New England-Canadian area and the Pennsylvania- West 

 Virginia area and between the latter and the Illinois- Western Kentucky 

 area. 



