THE PALEONTOLOGY OF MINNESOTA. 



Of the above the first nine numbers and a portion of the tenth may be considered as 

 representing the Galena, of Iowa, Illinois and Wisconsin, though that will do violence to 

 the lithologic criterion oa which Profs. Hall and Whitney, as well as Moses Strong, 

 determined the base of the Galena. But, as we will show further on, the shaly character 

 of the lower part of the Galena in Minnesota is merely a local feature of the group similar 

 to that which pertains more or less strongly also to the underlying divisions which we 

 parallelize with the Black River and Birdseye limestones of New York. Nos. 1 to 6 

 represent the whole of the Maclurea bed, and 7, 8 and 9, the Pusispira bed, while the 

 upper part of No. 10 is the Clitambonites bed. The lower part of No. 10 and the upper 

 part of No. 11 represent the "Upper Blue" and "Upper Buff" limestones of the 

 Wisconsin geologists and the Black River group of New York, while the lower part of No. 

 11, together with the whole of No. 12, corresponds with the "Lower Blue" and "Lower 

 Buff" limestones of Chamberlin, the Birdseye limestone of New York geologists, and the 

 Stones River group of Safford. 



While a dependence upon lithologic characters in classifying the Lower Silurian strata 

 of Minnesota is very liable to lead one into serious errors, the chances for overcoming the 

 difficulties are greatly increased when the faunal characteristics of the various beds 

 are minutely investigated and fully appreciated. This statement, however, is not to be 

 understood as intimating that the lithologic characters are either entirely unreliable or 

 useless in separating the beds. Qn the contrary, when judiciously employed in connection 

 with the evidence afforded by the fossils, they are of great assistance in determining the 

 age of the beds and in correlating even widely separated exposures of any of them. 

 Familiarity with the beds shows that the shales and limestones of each have certain 

 recognizable peculiarities, and there is something about the preservation and appearance 

 of the fossils of each sufficiently distinctive to enable an expert in such matters to 

 recognize, in at least nine cases out of ten, the bed and often the exact locality from which 

 they were collected. 



On the opposite page we present cuts of five actually measured continuous sections 

 showing the character and thickness of Lower Silurian strata in Goodhue and Pillmore 

 counties. None of the sections contain either the St. Peter sandstone or the lower part of 

 the Stones River or Birdseye limestone, and only one (No. 5) contains strata above the 

 Trenton. On another page, sections 6, 7 and 8 show the entire series of rocks, from the 

 St. Peter sandstone up, seen in the three counties of Ramsey, Goodhue and Fillmore. 

 These may be consulted to supplement sections 1 to 5, of which explanations follow. 



