AMERICAN GEOLOGY. 9 gical Map of Nebraska and Kansas, I see evidence of the existence of a portion of the Trias in his Permian. The Red Buttes on the road between Fort Laramie and Rock Indepen dence are certainly not Jurassic, though colored as such on Hayden’s map, but of the Triassic age as I said in my first Geological Map of 1853. I do not doubt that the Trias exists on both sides of the great Missouri valley, at the Black Hills, and on the border of the Plateau du Coteau des Prairies, con tinuing by the head waters of Red river to Lake Superior. As for the reliable paleontological evidence of the existence of the Jurassic in Nebraska, 1 do not think it in any degree more re liable than mine for New Mexico, and when you urged so earn estly in 1856 and 57 that there were no such formations as Jurassic and New Red in Nebraska, I maintained with no less certainty that they existed there, notwithstanding your repeated denials. Besides it will be just as easy for the learned Pale ontologist James Hall to prove that your Jurassic fossils from the Black Hills are identical with Cretaceous fossils of Fort Washita, as it has been for him to prove the supposed iden tity of my Jurassic fossils from Pyramid Mount with Fort Wa shita Cretaceous forms. Ninth. — I have not indicated the Permian between Fort Smith and Albuquerque, as I found unquestionable evidence of its existence only near the Rio Colorado Chiquito; but I have always strongly suspected that the New Red Sandstone between Delaware Mount and Beavertown was of Permian age. Having found no fossils, and being the first geologist to enter those regions, I was not able when in the field to declare exactly the age of those strata. All that I knew then was, that after having left the Carboniferous limestone of Delaware Mount, I entered upon strata belonging to another and younger formation; and it was only after having passed Beavertown that 1 saw clearly I was upon the New Red Sandstone. Since the discovery of Permian in Kansas I am still more inclined to the belief that the strata between Delaware Mount and Beaver town are Permian. Thus you see I include the Permian in
