150 THE DEVONIAN AND CARBONIFEROUS. [bull. 80. 



brown encrinital group of Hannibal," and what Swallow and Shumard 

 bad called the ik encrinal limestone " in Missouri. 



Owen's name " Keokuk cherty limestone," with " cherty " omitted, 

 is adopted for the next division, and the author writes, u the so-called 

 siliceous formations of Tennessee and Alabama are of the same strata." 1 

 This division includes the three divisions d, e, and /of Owen's classifi- 

 cation, viz, the " Keokuk cherty limestone," the " shell beds," and the 

 11 Archimedes limestone." 



Omitting the " Geodiferous bed" of Owen as " beds of passage," 2 Hall 

 applied the name "Warsaw or Second Archimedes limestone" to the 

 "Magnesian limestone" and "Gritstone" of Owen. The next higher 

 division is called the " St. Louis limestone." 



D. D. Owen, io a letter 3 to M. de Verneuil, referred to the discovery by 

 Shumard of the "St. Louis limestone" which, Owen thought, "belonged 

 in the lower part of the Carboniferous limestone." This appears to be 

 the earliest announcement of the St. Louis limestone in the scientific 

 sense. The name was definitely proposed and defined by Dr. H. King 

 of St. Louis in 1851, 4 and in Owen's table the " lower concretionary 

 limestone " includes the " limestone of St. Louis." 



Above the St. Louis limestone is reported the " Ferruginous sand- 

 stone" of Missouri. Owen did not report such a member, but for the 

 overlying limestone series (composed of heavy-bedded limestones, and 

 generally alternating with marl, shale, limestones, and a few beds of 

 sandstone), Hall proposed the name " Kaskaskia limestone or Upper 

 Archimedes limestone." This formation was found both at Kaskaskia 

 and at Chester, Illinois, and below St. Genevieve in Missouri, and ac- 

 cording to A. H. Worthen had been examined, its position clearly de- 

 termined, and reported upon under the name " Chester limestone " 6 by 

 himself in 1853. It is probable that Owen did not recognize this higher 

 limestone, and that his "/', upper concretionary limestone," may be only 

 a continuation of the " lower concretionary," d', separated from it by a 

 more or less local sandstone, e'. 



Evidence was given of extensive denudation previous to the coal 

 period, and the author mentioned as consequences of this ancient de- 

 nudation, the coal deposits in depressions among the inclined strata of 

 the Silurian rocks ; also rounded masses of clay found in the limestones 

 of the Hamilton and Upper Helderberg groups, and he concluded from 

 examination that these masses of clay and coal deposits were made 

 subsequently to the deposition of the limestone, filling cavities caused 

 by denudation. 



In conclusion, a few words express the general features of the series 



1 Hall, James: On the Carboniferous limestones of the Mississippi Valley. (Abstract.) Am. Jour. 

 Sei., vol.23, 1857, p. 190. 



2 In the final Report on the Geology of Iowa, 1858, this bed is included with the Keokuk limestone, 

 p. 96, 



3 Dated January 14, 1819, and published in the Bull. Soo. g6ol. France, II, voL 6, pp. 419-441. 



4 Proc. Am. Assoc. Adv. Sci., vol. 5, p. 185. 

 6 See Geol. of Illinois, voL 1, p. 41. 



