182 THE DEVONIAN AND CARBONIFEROUS. [bull. 80. 



York is absent in consequence of subsequent denudation; that the 

 "Old Red" is not necessarily all Devonian in age ; that in the Marshall 

 are some species which are considered as "having near analogues in the 

 Old Bed of Scotland;" that the Catskill, although identified as the 

 equivalent of the Old Ked sandstone of Scotland and Wales, is younger 

 than that part of the Devonian represented in New York by the Chemung 

 and its equivalents in Europe, and as the Marshall has been shown 

 to be not the equivalent of the Chemung in New York, it must be, the 

 author argued, the representative of the Catskill. 



At the close a table of geological equivalents is given. The part of 

 it of chief value here is that expressing the author's interpretation of 

 the equivalents of the Marshall group of Michigan, which consists of the 

 following, immediately overlying the Huron group, in ascending order: 



(1) Huron gritstones, bluish or greenish gray, fine grained, regularly bedded, 15 feet. 



(2) Marshall sandstone, reddish, yellowish, olive, obliquely laminated, highly ferru- 



ginous; the iron often a rudely concentric, concretionary arrangement; in 

 places calcareous, highly fossiliferous, 160 feet. 



(3) Napoleon saudstone, pale buff, often conglomeratic, obliquely laminated, thick 



bedded, 123 feet. 

 Followed above by the Michigan salt group. 



According to the table the equivalents to these are, in New York, 

 upper part of Catskill group, including " Carboniferous conglomerate" 

 and "Chemung conglomerate;" in Ohio, "Waverly series, in part" 

 (the "Chocolate shale series" and the " base of the Waverly series" are; 

 correlated with the Chemung and Portage of New York); in Indiana, 

 the "Rockford limestone" and "Williamsport gritstone;" in Illinois, 

 the " Kinderhook group;" in Iowa, the "Yellow sandstone series;" in 

 Missouri, the "Chouteau limestone," "Vermicular sandstone," and 

 shales, and "Lithographic limestone;" in Tennessee, part of the 

 " Siliceous group" and the " Siliceous shales," aud in Europe the " Old 

 Red saudstone" of Scotland, "Yellow sandstone" of Ireland, and the 

 " Westphalian schists." 



In 1871 appeared the Report of Progress of the Geological Survey of 

 Ohio. 1 



Two of the chapters have matter of interest in the present discussion : 

 One by Mr. E. B. Andrews, 2 ; a second by Mr. M. C. Read. 3 



The formations discussed in Mr. Andrews's article are the " Ohio black 

 shale" or "Huron shale," the "Waverly sandstone," the "Maxville 

 limestone," the " Conglomerate" of the Coal Measures, and the Coal 

 Measures. 



The Waverly sandstone is divided into three parts. The middle is 

 coarse and often a conglomerate ; the division above, a fine-grained 



sandstone, and that below sandstones and shales, with interstratified 



» 



1 Geol. Survey Ohio, Rep. Progress in 1870 ; Columbus, 1871. 



2 Report of Labors in the Second Geological District during the year 1870 in Coal Measure 

 district, pp. 55-251. 



3 Sketches of the Geology of Geauga and Holmes Counties, pp. 463-484. 



