28 T. E. Savage — Relations of the Alexandrian Series. 



Art. II. — The Relations of the Alexandrian Series in 

 Illinois and Missouri to the Silurian Section of Iowa • by 

 T. E. Savage. 



Among the criteria employed in determining the geological 

 position of strata, their fossil content and stratigraphic rela- 

 tions are conceded by almost all geologists to be of the highest 

 value, and to rank first in importance. A notable example 

 of the error likely to result from disregarding these reliable 

 criteria in making correlations, and reversing the usual order 

 of procedure by " directly applying the broader paleogeographic 

 principles to the solution of local problems in stratigraphy," is 

 shown in a recent paper by Charles Keyes entitled " Paleo- 

 geographical Affinities of the Alexandrian Series."* 



In this paper Keyes discusses the strata of the Edgewood 

 formation as developed in the vicinity of Louisiana, Missouri, 

 recently described by the writer, f and asserts (1) that there is 

 a marked plane of unconformity present at the base of the 

 Bowling Green limestone member ; (2) that the Bowling 

 Green limestone member represents an overlap of a northern 

 Silurian formation upon an earlier southern deposition 

 represented by the underlying portion of the Edgewood forma- 

 tion ; and (3) that the stratigraphic affinities of the Bowling 

 Green limestone member are with the Gower limestone in the 

 upper part of the Silurian section of Iowa, with which he 

 thinks it should be associated. It is unfortunate that no facts 

 are presented in support of these assertions, as geologists are 

 left without means of properly judging with regard to the 

 source and merits of the data upon which the statements are 

 based. 



In my paper on the Alexandrian series;}: the Bowling Green 

 limestone member was shown to be closely allied to the under- 

 lying strata of the Edgewood formation, and it was clearly 

 shown that this limestone was unconformable overlain by the 

 Sexton Creek limestone, which corresponds in general age to 

 that of the Brassfield of Indiana, Ohio, and Kentucky. Con- 

 siderable additional information on the strata of the Alexandrian 

 series of the Upper Mississippi valley has been obtained by the 

 writer during the summer of 1913, all of which completely cor- 

 roborates the views of the Bowling Green limestone member 

 presented in my paper above mentioned. They show con- 

 clusively that the affinities of this limestone are with the Edge- 

 wood formation, and that, stratigraphically, this upper member 



*This Journal, vol. xxxvii, pp. 254-256, 1914. 



fBull. Geol. Soc. America, vol. xxiv, pp. 359-376, 1913. 



| Ibid., pp. 359-361, 1913. 



