TO JUNCTION OF GRAND AND GREEN RIVERS. 19 



by the prairie-grass or beneath the widely-spread Drift deposits over which passes the 

 greal thoroughfare of the Sante Fe" road. As far as I could sec or learn, however, the 

 Coal-Measure8 are there generally barren of useful minerals. The iron-ores and the 

 fire-clays, so abundantly associated with the coal-beds in Ohio and Pennsylvania, are 

 almost entirely wanting, and but a single outcrop of a coal-seam of workable thick- 

 ness — thai of Burlingame, described in my former report — is known in the vicinity of 

 our route. The coal-strata of this region are, however, not only less numerous, but 

 less continuous than are those east of the Mississippi, and it is highly probable that 

 local but valuable deposits of mineral-fuel will hereafter be discovered where their 

 existence is not now suspected. 



At DraffOOn Creek we reach the extreme summit of the Carboniferous formation, 

 and first meet with those which may be regarded as distinctly Permian. As has been 

 remarked, in the discussion of this question on a former occasion, it is exceedingly 

 difficult, if not impossible, to separate these two formations in this region by any well- 

 defined line This is clearly shown also by the able analysis of the geological struc- 

 ture of Kastern Kansas by Messrs. Meek and Hayden, and Swallow and I lawn, and 



especially by the difference of opinion which still exists among these gentlemen as to 

 where the line of demarcation should be drawn. The rocks of that country are conform- 

 able throughout, and the materials composing them are so similar as to indicate great 

 uniformity in the physical conditions which attended their deposition. The fossjls 

 which they contain must therefore be our only guide in their classification ; and these. 

 though numerous and well marked, are so distributed as to give fair ground for con- 

 siderable difference of honest opinion 



Beneath the variegated non-fossiliferous series of the Trias, are certain beds of 

 magnesian limestone which contain a large number of fossils, for the most part gener- 

 ically identical with, and specifically closely allied to, the most characteristic forms of 

 the Permian of Europe. These consist of species of Bakevellia, Leda, Axinus, Monotis, 

 Pseudomonotis, Myalina,Pleurophorous, Productus, Athens, ('/«>>/<'/<■*, Nautilus, BeUerophon, 

 Murchisonia, &c. ( )f these one species of Monotis, and another of Myalina, are scarcely 

 distinguishable from those whicn occur in the Coal-Measures below, though very possi- 

 bly distinct. The AthyHs, however — a variety of A. subtUlta, but broader and more 

 gibbous than the common form — recurs in the underlying strata with a fauna decidedly 

 Carboniferous. The same is probably true of a species of BeUerophm common in these 

 magnesian limestones. The Productus mentioned (/'. Calhomianus) is scarcely differ- 

 ent from /'. scm'nrliculdtus. With the possible exceptions 1 have enumerated the fauna 

 of this group is decidedly Permian in character: and if the Permian formation is to be 

 regarded as distinct from the Carboniferous, which is scarcely to be doubted, although 

 the separation would not have been made if our American strata had been the basis of 



geological classification, this upper group of magnesian limestones should undoubtedly 



be called Permian. Below the magnesian rocks to which I have referred, occur numer- 

 ous alternations of magnesian limestones and variously-colored (days which contain a 

 min<>-liim- of Carboniferous and Permian fossils, or perhaps more properl v a mingling of 

 the species contained in the upper group of magnesian limestones with others common 

 in the Carboniferous strata below, added to which are a few species that seem to be 



