

williams.1 CONRAD, WHITTLESEY, MURCHISON. 43 



thought to "rank with the Mountain limestone of Europe, and rest on 

 the Old Red sandstone." ! By the latter term he evidently meant the 

 Medina sandstone. 



In 1839, T. A. Conrad published " Notes on American Geology."* 

 He used the term "Trilobite rocks" for what had previously been 

 called the Transition or the Silurian system. In this paper he stated 

 that " Strophoraena is the most characteristic of the Trilobite system ;" 

 that "Producta has as yet been found only in the upper term," or 

 " Pyritiferous rock" of Eaton, and that the "Producta is abundant in 

 the Mountain limestone where Strophomena is rare," and that this 

 genus is " eminently characteristic of the Carboniferous system." This 

 indicates a careful observation of fossils, although the identifications 

 are broader than customary at the present time. 



In 1839, Whittlesey, Ch., recognized the following classification of 

 the rocks of Ohio : 



1. Coal Measures. 



2. Conglomerate. 



3. Waverly series. 



4. (Black shale, Hamilton and Marcellus). 



5. Cliff limestone (including Coruiferous and Onondaga). 



The "Hamilton and Marcellus shales" extended from the lake to the 

 base of the Newburg section. " Chemung and Portage" included the 

 rocks of Newburg and Bedford and above to about halfway to Hudson. 



Murchison, in his "Silurian System," 3 London, 1839, proposed the 

 following names. 



Oolitic sj stem. 4 Silurian system. 8 



New Red system. 5 Upper Silurian rocks. 9 



Carboniferous system. 8 Lower Silurian rocks. 9 

 Old Red system. 7 



and quotes the term " Cambrian System," 7 from Prof. Sedgwick. The 

 words, " Oolitic," "New Bed," il Carboniferous," "Old Red," were names 

 used before and applied to certain rocks, but their use in connection 

 with the word, " system," is apparently introduced for the first time by 

 Murchison. „ 



The following is the classification proposed by Murchison as it ap- 

 pears upon his map : 



a. Inferior oolite ) 



b. Upper lias and marlstone £> Oolitic system. 



b. Lower lias ) 



c. Upper red marl ) 



c. Keuper sandstone j 



J Lower Red marl I New Red system. 



a. New Red sandstone ( J 



e. Calcareous Conglomerate (Magnesian limestone) 



/. Lower New Red sandstone J 



1 Am. Jour. Sci., vol. 3^, page 123. 



2 Ibid., vol. 35, pp. 237-251. 



•The Silurian System, founded on Geological Researches in the counties of Salop, Hereford, Radnor, 

 Montgomery, Caermarthen, Brecon, Pembroke, Monmouth, Gloucester, Worcester, and Stafford, with 

 descriptions of the coal fields and overlying formations. By Roderick Irapey Murchison, F. R. S.-, etc. 

 In two parts. Loudon, 1839. Quarto, 708 pp., 37 plates, and large folding map. 



4 P. 13. 6 P.27. 6 P. 79. 7 P.1G9. «P.195. 'P.265. 



