AMERICA. 113 



coal-field a seam 3 feet thick is worked, on account of its value for gas 

 and coke ; iron also exists here. Analyses of the ores are given. 



G. A. L. 



Clark, R. IST. The Tertiary Coal-beds of Canyon City, Colorado. 

 Trans. Amer. Inst. Min. Eng. vol. i. pp. 293-298, map. 



These coal-bearing rocks are about 600 feet thick, and contain at 

 least nine seams, from 8 inches to 6 feet in thickness. They extend 

 over about 34 square miles, and consist of sandstones and shales. " The 

 shales and slates contain but few fossils ; the sand-rocks are full of the 

 leaves of the oak, the Cinnamomum, and the CalamopslsJ^ F. W. R. 



CoMSTOCK, T. B. Addendum to Article xlvii. vol. vi. Amer. Journ. 



p. 151. 

 Letter stating that a review of the writer's Silurian fossils from the 

 Wind-lliver mountains has resulted in the discovery that this forma- 

 tion is made up of rocks of the Quebec group of the Calciferous Epoch, 

 overlain by a considerable thickness of the Niagara Limestone. The 

 last and the Oriskany Sandstone are new to this region. The age of 

 the Bridger and Green-River groups is in dispute (Miocene or Eocene). 



G. A. L. 



Cope, Prof. [E.]. On the age of the Lignite and other corresponding 

 formations of the West, and especially its supposed equivalent in 

 Northern Colorado. Proc. Ac. Nat. Sci. Philadel. part 1, pp. 12, 

 13, also p. 10. 



The beds are regarded as Cretaceous, on the evidence of their ver- 

 tebrate remains. 



Cox, Prof. E. T. Eifch Annual Report of the Geological Survey of 

 Indiana, made during the year 1873. Pp. 494, 4 maps in cover. 

 8vo. Indianapolis. 



Consists of the usual detailed reports of the examination of various 

 parts of the State of Indiana by the divisions of counties, each of which 

 is illustrated by a special map. The counties particularly noticed are 

 chiefly in the southern portion of the State, in the district between the 

 Ohio and the Wabash River, the special reports being by W. W. 

 Borden, J. Collett, and G. M. Levette. The rocks are chiefly of the 

 Subcarboniferous Limestone series, but in parts lower rocks down to the 

 Hudson River or Cincinnati group of the Lower Silurian series. A 

 noticeable feature appears to be the intercalation of beds showing marine 

 conditions in the Carboniferous series as we pass southward, the coal- 

 bearing rocks being in places found to contain thick beds of limestone 

 witli a corresponding impoverishment in coal. There are numerous 

 analyses of coals, especially with regard to their coking power, and of 

 iron-ores, in different parts of the report, according to their occurrence 

 in the different counties. The manufacture of cement, which is now 

 carried on to some extent in Indiana, from the more argillaceous beds 

 of limestone, is described in detail, with analyses of the materials em- 

 ployed. Details of the agricultural conditions of tho country, especially 



1874. I 



