87 



did not answer my letter, and I supposed, from Ms silence, that he was 

 content to leave the matter as it was, until further researches were 

 made ; but Mr. Meek having called the attention of the readers of 

 Silllman's Journal, vol. xxxi. Jan. 1861, p. 127, to the views of Dr. 

 Shumard in opposition to mine, and taken special care to indorse his 

 own previous opinions and those of his friends and collaborators, 

 Messrs. James Hall, Dr. Hayden, and Drs. Shumard and Newberry, 

 on the disputed geological age and order of succession of the strata 

 in the West, I must once more try to disentangle the thread that 

 my learned adversaries endeavor to keep in a constant imbroglio, and 

 state again what I candidly suppose to be the truth, taking for a basis 

 my own observations. 



In the First Report of the Progress of the Geological and Agricultural 

 Survey of Texas, December 1, 1859, Dr. B. Shumard says: "]Mr. 

 Marcou, in his Carte Geologique des Etats Unis, has attempted to 

 define the limits of our coal measures. But the boundaries laid down 

 by him are incorrect, and liable to lead to serious error. The coal 

 measures do not extend into Grayson, Fannin, Collin, and Dallas 

 counties, as represented in that map." 



If Dr. Shumard will reduce a map of Texas, containing the county 

 boundaries, to the very small scale of my Carte Geologique des Etats 

 Unis, he will see that I have not placed any coal measures in Grayson 

 and Fannin counties, and it is doubtful if I have put any into CoUin 

 and Dallas counties, for one or two lines will easily take out a county 

 on such a reduced scale. On such a map, colors can only give a general 

 idea of the distribution of the principal groups of the sedimentary 

 and crystalline rocks. Geological landmarks must be looked for there, 

 and not the geological details of the counties. In my first geological 

 map of the United States, pubKshed in Boston, 1853, I showed the 

 union of the coal fields of Missouri and Iowa with that of Arkansas, 

 which Mr. James Hall said, in the SiUiman's Journal of March, 1854, 

 was " without authority," p. 205, vol. xvii. It is true that ]\Ir. 

 Hall himself united these coal fields in 1857, in his Geological Map of 

 the Country loest of the Mississippi, and Mr. H. D. Rogers did the 

 same in 1856, both of them copying me, and I suppose sustained by 

 good authority. 



During my exploration of Ai'kansas and the Choctaw and Chickasaw 

 countries in 1853, I perceived that the coal measures must extend 

 into Texas ; and from the collections of Capt. Pope, submitted to me 

 at Boston in 1854, on his line of exploration from Preston to El Paso, 

 by Fort Belknap, I concluded that the coal field did not stop in 

 Arkansas, but extended into Texas as far as the Clear Fork of the 

 Rio Brazos west of Fort Belknap. Aided by the observations of Dr. 

 Roemer on the Rio San Saba, published by that learned geologist in 



