lxxxiv 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 oun 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 Fusispira 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. On 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 Fillmore 
counties. None of the sections contain either the St. Peter sandstone or the lower partof — 
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. 
