42 TnE DEVONIAN AND CARBONIFEROUS. [buluBO. 



Pennsylvania: XL D. Roofers had been studying the rocks of Penn- 

 sylvania, and there was published in this year a generalized section of 

 the Appalachian region of Pennsylvania.* The formations recognized 

 by Rogers were as follows : 



( 1. Sandstone of South Mountain. 



2. Limestone of Kittatiny Valley. 



3. Slate of Kittatiny Valley. 



4. Sandstone and conglomerate of Kittatiny Valley and Blue Mountain. 



5. Red and variegated sandstone and shale of the valley northwest of Kitta- 



tiny. 



6. Bine limestone along the north base of Kittatiny and both sides of Montour's 



Ridge. 



7. Sandstone of the first ridge north of Kittatiny. 



8. Olive-colored slate of the valley between Kittatiny and second mountain 



J. Led sandstone and shale of southeast slope and base of Alleghany Moun- 

 tains. J 



10. Sandstone and conglomerates of second mountain, and of southeast summit 



ot Alleghany. 



11. Red shale of anthracite coal regions. 



12. Conglomerates and sandstones immediately below the Coal Measures (Broad 



Top and Alleghany coal region) 



13. Anthracite Coal Measures. 



It is interesting to note that this system of numbers for the various 

 formations was made out about the same time that the system of no- 

 menclature adopted by the New York Survey was being formed. Both 

 systems have struggled for existence in some parts of the country 

 The system of Rogers was one based strictly upon the nature of the 

 rocks and their stratigraphic sequence, and in so far is satisfactory for 

 that particular region ; but the New York system was denned in addi- 

 tion by the fossil contents of the various formations, and an attempt 

 was made at the very start to correlate them with the several forma- 

 tions defined by the European geologists. 



Whether we adopt local geographical names or not, it is doubtful if 

 simple numbers, as proposed in the Pennsylvania system of Rogers, 

 will ever be satisfactory except for a limited region. 



In this same year, 1838, we have a report upon the Upper Illinois, 

 by C IJ. Shepard.* The name « Maguesian limestone" is applied to 

 he "great limestone rock formation extending from near Chicago to 

 the Kankakee River," and in various places the coal formation was 

 recognized. Several sections of the coal formations and descriptions 

 and figures of some plants and fossil shells are given. 



Prof. Dewey, of Rochester, gave an account 3 of some observations 

 on the rocks in western New York. The rocks south of Rochester 

 were misunderstood by him on account of the misinterpretation of the 

 fossils; for instance, the "limestones" were regarded as the same as 

 those of Trenton Fails, and as belonging to the Transition, and were 



• See Am. Jour. Sci., vol. 34, pp. 189, 190. 

 2 Ibid., pp. m-161. 

 ■Ibid., vol 33, pp. 121-123. 



