CARBONIFEROUS. 367 



midway between Fort Mason and Fort McKavett, the rocks of the group are 

 seen cropping out extensively from beneath thick strata of the Cretaceous 

 Period. At this locality the thickness of their exposed edges was estimated 

 by myself at about two thousand five hundred feet;" but in his Journal, pub- 

 lished in the same book, he says of the same locality, " We came to an ex- 

 tensive outcrop of hard, granular limestone, belonging to the Upper Division 

 of the Carboniferous system, which is here to be seen emerging from beneath 

 the Cretaceous strata." * 



It will be seen from the above that he calls it Sub-Carboniferous in one 

 place, and puts it in the Upper Division in another; and as the fossils he 

 gives as coming from the beds are similar to a collection made near Brady 

 by myself from the Upper Division of the Carboniferous, I conclude his 

 reference to the Sub-Carboniferous was a mistake, and therefore need not be 

 further noticed. 



It has been thought that the limestones of Palo Pinto and other counties 

 belonged to the Sub-Carboniferous, because of its great extent and thickness, 

 under the mistaken notion that the Coal Measures did not anywhere contain 

 such extensive beds of limestone. 



The same mistake was made in the early explorations of Iowa. Dr. C. A. 

 White, in speaking of this matter, says:f "We find the formation in Iowa 

 to be as fully characterized by limestones as any of formations of the Sub- 

 Carboniferous group are." 



From all the evidence I have been able to secure in the course of my 

 work in this district I am forced to the conclusion that up to the present no 

 Sub-Carboniferous rocks have been discovered. 



CARBONIFEROUS. 



By the term Carboniferous 1 intend in this report to designate the Coal 

 Measures as the name was first applied by the miners in England to the coal 

 bearing strata of that country, and to say when speaking of the Coal Meas- 

 ures, that it occupies the same relative position in the geological horizon as 

 that applied to the locality where the name was first used, and as is given 

 generally in the text- books. 



I have not attempted to subdivide the strata into Upper Coal Measures, 

 Middle Coal Measures, and Millstone Grit, as has been done in other States, 

 nor to correlate the Texas divisions with other localities, for the lack of time 

 to study the fossils of the measures, but have adopted provisional divisions of 

 the formation, and hope to be able at a future time to correlate the strata 



* A Partial Report on the Geology of Western Texas, Dr. Geo. G-. Shumard, Austin, 1886. 

 f Geology of Iowa, 1870. 



