144 APPENDIX D. GEOLOGY. 



in Texas, as already described, may in some districts protrude through 

 the coal measures. But if coal does actually exist beneath the newer 

 rocks, it may be reached, as it has been in like instances in Europe, 

 although no trace of it exists at the surface. 



The above suggestions may seem to embrace .a very wide field for a 

 coal deposite. But on locating the several patches of coal upon a map 

 of the United States, I was struck with one fact. Starting -with the 

 beds marked upon Monk's map, in the southwest part of Texas, and 

 running the eye along the range of carboniferous limestone described by 

 Dr. Roemer, we come to the coal at Fort Belknap ; next to the exten- 

 sive deposite lying between Forts Washita and Smith, in the west part 

 of Arkansas ; and all the way we find ourselves almost in the range of 

 the great coal field of Iowa and Missouri, as mapped by Dr. Owen ; and 

 it seems to me that every geologist will at once infer that the Missouri 

 field does follow this line, not only across Arkansas, but also through the 

 Choctaw Nation, and probably across Texas — interrupted, probably, in 

 many places by the protrusion of older rocks, and in others covered by 

 newer formations. I have a considerable degree of confidence that such 

 will ere long be found to be the fact, even if we leave out the other coal 

 deposites further west and northwest. And should the result of your 

 explorations be to bring out such a development, I think you must feel 

 rewarded for your fatigues and privations. 



That some of the cases above described may turn out to be tertiary 

 coal is quite possible, especially those along the base of the Rocky 

 mountains ; for it is well known that much farther to the north such coal 

 is developed on a large scale, especially along Mackenzie's river, even to 

 its mouth, on the Arctic ocean. Nor is it always easy for those not 

 practised mineralogists to distinguish this coal, especially from anthracite. 

 Dr. Owen describes the southernmost bed of brown coal on the Mis- 

 souri (from four to six feet thick) as having " the aspect of ordinary 

 bituminous coal," yet as " smouldering away, more like anthracite." 

 (Report, p. 196.) Even such coal might be of great value ; but I can- 

 not believe that much of that described above, especially that on the 

 line above indicated, will prove to be tertiary coal. 



I ought to have mentioned, that among the specimens in my hands 

 is one of lignite, collected July 3, near the sources of Red river, not far 

 from the "Llano estacado," and within the limits of the gypsum deposite 

 to be described. It is an exceedingly compact coal, and burns without 

 flame, emitting a pungent but not bituminous odor. It is doubtless 

 tertiary or cretaceous ; but I think, if in large masses, it might easily be 

 mistaken for anthracite. 



