WALCOTT.J MISSOURI. 199 



posed subdivisions." This contains a critical review of the published 

 papers upon the age of the copper-bearing rocks of Michigan, Wisconsin, 

 and Canada. 1 



In their observations on the junction between the Eastern sandstone 

 and the Keweenaw series Messrs. Irving and Chamberlin published a 

 map of Keweenaw Point, showing the distribution of the Eastern sand- 

 stone to be confined to the southeastern side of the poiut, the northern 

 and northwestern sides being formed of the Keweenaw series. 2 They 

 discuss the views held by Messrs. Jackson, Foster and Whitney, Agas- 

 siz, Rominger, and Oredner upon the stratigraphic position in the geo- 

 logic series of the Eastern sandstone and the sandstones of the Kewee- 

 nawan series ; and give also a detailed account of the contact between 

 the sandstone and the Keweenaw rocks. 



MISSOURI. 



The first notice we have of a sandstone about the Ozark Mountains of 

 southeastern Missouri is by Dr. Edwin James in 1822, who called atten- 

 tion to an inclined sandstone, like that of the Alleghany Mountains, 

 between which and the granite there intervened a stratum of clay 

 slate highly inclined and resembling the primitive clay slate of New 

 England. 3 



This was followed twenty-nine years later by a sketch of the geology of 

 the State of Missouri, in which Mr. H. King describes what he calls the 

 second magnesian limestone. Beneath this is a sandstone which he 

 was inclined to correlate with the Potsdam sandstone of New York. 

 The presence, however, of Lituites, Euomphalus, Pleurotomaria, Nat- 

 ica? was opposed to this view, but the stratigraphic and lithologic 

 evidence sustains the correlation. In order to explain the presence of 

 the fossils he suggests that " this may be an independent formation 

 not represented in New York or elsewhere, and yet nearly contemporary 

 with the first evidences of organic existence there and to be associated 

 with them in the same geological epoch." 4 



The work of the first Missouri survey proved the presence of four 

 magnesian limestones with a belt of sandstone between the third and 

 the fourth, the fourth limestone forming the base of the series. Prof. 

 G. 0. Swallow describes the third sandstone, above the fourth magne- 

 sian limestone, as a white saccharoidal sandstone, made up of slightly 

 cohering transparent globular and angular particles of silex. It is as- 

 signed a thickness of 30 feet, and owing to its position below the third 

 magnesian limestone is considered at least as old as the Caiciferous 

 saudrock, and there is great probability that it may prove to be beneath 



1 The Azoic system and its proposed subdivisions. Harvard Mus. Comp. Zool. Bull., vol. 7, 1884, pp. 

 482-498. 



2 Observations on the j unction between the Eastern sandstone and the Keweenaw series on Keweenaw 

 Point, Lake Superior. U. S. Geol. Surv. Bull. , No. 23, 1885, pi. i. 



'Geological sketches of the Mississippi Valley. Phil. Acad. Sci., Jour., vol. 2, 1822, p. 329. 



4 Some remarks on the geology of the State of Missouri. Am. Assoc. Proc, vol. 5, 1851, pp. 190, 191. 



