EARLIER STUDIES AND INTERPRETATION OF STRATA 355 



1870, Worthen 11 did not distinguish the Alexandrian series from the 

 Niagara limestone. 



In a report on the Geology of Lincoln -County, Missouri, published in 

 1873, W. B. Potter 12 referred the oolite present in the ridges and knobs 

 in the northeast part of this county to the Onondaga of the Devonian. 



In a paper entitled "A remarkable fauna at the base of the Burlington 

 limestone in northern Missouri," in 1892, Dr. C. E. Keyes 13 distin- 

 guished the white oolite bed and the overlying buff or brown limestone 

 exposed near Louisiana and correlated them with the Niagara limestone 

 of Iowa, 



In describing the vertical range of fossils at Louisiana, Missouri, in 

 1897, Keyes and Eowley 14 again referred the oolite bed and the associated 

 buff limestone in this region to the Niagara. 



In the following year Keyes 15 published a paper on "Some geological 

 formations of the Cap Au Gres Uplift," in which the name Noix oolite 

 was proposed for the white oolite bed in the vicinity of Louisiana, and 

 the term Bowling Green limestone was given to the buff magnesian lime- 

 stone near Bowling Green, Missouri. Of these formations Keyes writes : 



"The Noix oolite and the Bowling Green limestone together may be regarded 

 approximately as equivalent to the so-called Niagara of the Upper Mississippi 

 basin." 



In his report on the geology of Pike County, Missouri, in 1907, E. E. 

 Eowley 16 says: 



"The Silurian is represented by a white oolitic and a brown limestone. The 

 oolitic limestone attains a thickness of about 7 feet, and from its fauna is 

 thought to belong to the Clinton. The brown limestone overlies the white 

 oolitic and attains a maximum thickness of 25 feet. This horizon is clearly 

 Niagara." 



In a paper by the writer 17 in 1908 a bed of cherty and mottled lime- 

 stone in southwestern Illinois was recognized as the equivalent of some 

 part of the Brassfield limestone of Ohio. A distinct formation of early 

 Silurian time was also shown to be present in this region below the Brass- 

 field and above the Girardeau and separated from each by a sedimentary 



" A. H. Worthen : Ibid., pp. 6, 7, 26, and 207-240. 



12 W. B. Potter : Geological Survey of Missouri, 1873, p. 242. 



13 C. R. Keyes : Am. Jour. Scl., vol. xliv, 1892, p. 447. 



"Keyes and Rowley: Proc. Iowa Acad. Scl., vol. iv, 1897, pp. 26-40. 

 , 16 C. R. Keyes: Ibid., vol. v. 1898, pp. 58-68. 



"R.R.Rowley: Missouri Bureau of Geology and Mines, 2d ser„ vol. vili, 1007, p, 20. 



17 T. E. Savage: On the Lower Paleozoic stratigraphy of southwestern Illinois. Am. 

 Jour. Scl., vol. xxv, May, 1908, pp. 431-443. 



