404 On American Geological History. 



showed that the Sikirian, Devonian, and Carboniferous strata^ 

 which were originally laid out in horizontal layers, were after- 

 wards pressed on to the north-westward, and folded up till the 

 folds were of mountain height, and that thus the Appalachians 

 had their origin ; and that also, by the escaping heat of those 

 times of revolution, extensive strata were altered, or even crys- 

 taUized.* 



* As I have already remarked, many names are' above omitted which 

 Eave contributed largely to our knowledge of American Geology. 



While Dr. Morton was the first to distinguish the Korth American 

 Cretaceous beds, and pursued his researches with great energy and skill* 

 they have been largely studied also by Lyell in different localities on the 

 east and south, by I^icollet and recently Shumard, Haydex, Meek and 

 Hall, on the beds west of the Mississippi, by Roemer in Texas, Tuomey in 

 South Carolina, H. D. Rogers and otliers in N'ew Jersey, J, W. Bailey with 

 reference to microscopic species, and J. Leidy for Vertebrate Remains. 



The Tertiary has been investigated by Lyell along both the eastern and 

 southern border ; also in different localities by Morton, M, Tuomey, F. S. 

 KoLMEs, C. S. Hale, I. Lei, H. D. and W. B. Rogers, Roemer, J. D. Dana 

 and W. P. Blake for the tertiary of the Pacific coast, Bailey for minute 

 species, Harlan, Owen, Muller, Prout, Leidy, Wyman and Gibbes, for 

 Vertebrate fossils; while these and many other authors have published on 

 the post-tertiary deposits and organic remains. 



The Silurian and Devonian systems have occupied the attention of 

 nearly all who have written on American Geology, in the East or West, 

 among whom, there are : — Hall, Mather, Vanuxem, Emmons, Conrad, De 

 Vernedil of Paris, the Professors Rogers Messrs. Whitney and Foster, D. 

 D. Owen, C. T. Jackson, D. HocCtHton of Michigan, G. Troost and lately 

 J. M. Safford of Tennessee, J. Greene, J. Loce:e, C. Whittlesey, I. A. 

 Lapham, G. C. Swallow, J. G. Norwood, B, F. Shumard, besides the 

 investigators in Canada, Sir W. E. Logan, J. Bigsby, J. W. Dawson, T. S. 

 Hunt and others. 



The Carboniferous formation was early studied in many of its details by 

 Dr. S. P. Hildreth. But the successive strata of the whole formation 

 from the Devonian through the Subcarboniferous and Coal Measures, were 

 first systematized by the Professors Rogers, though without yet marking 

 out in any of their publications the subdivisions of the coal measures them- 

 selves and the characteristic fossils of each, as had been done for the Devo- 

 nian and Silui^fan by the New York Geologists. Other researches on tlie 

 coal beds have been made by R. C. Taylor and J. P. Leslie in Pennsylva- 

 nia, J. Hall, D. D. Owen, and others in the states of the Mississippi valley, 

 J. S, Newberry on the fossil plants and fishes of the Ohio coal measures, 

 Hitchcock and C.T. Jackson on the coal beds of Rhode Island; Dawson, 

 Lyell, Jackson, &e., on the new Brunswick and Nova Scotia beds ; Lea, 

 Wyman, Leidy, Lyell and Dawson on Reptilhan and other carboniferous 

 fossils. 



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