THE LOWER SILURIAN SECTION. 



359 



beds vary somewhat in thickness and dip in certain localities. The dip 

 of these rocks in Minnesota is not uniform over any large area, but weak 

 anticlinals and synclinals are frequent. The Galena dips several degrees 

 toward the south in the quarries near Owatonna; in the quarry at Ken- 

 yon there is a marked synclinal and at Faribault a slight dip ; at Cannon 

 falls (in N. E. \ sec 31, T. 112, R. 18 \V.) the beds of the Galena are so 

 much below those of a neighboring lower horizon (in sec. "2'.), same town- 

 ship) as to be confusing unless lithologic and paleontologie data are relied 

 upon. The Lower Silurian in Minnesota is undulating as in Wisconsin, 

 only not in so strong folds. 



The following is a summary description of the several beds (figure 5) : 



r-i 



3 



I 



! 



i 



i 



WyXoff beds 



So: 



Maquoketa Shale zo'. PI 



Maclurea bed 



Llngulasma bed 



Camarella bed 



Orthisina bed 



Zysrospira bed 



Fucoid bed 



¥ 



k 





Stictopora bed 



St let op ore I la J>ed 

 Blue Limestone 



Buff Limestone 



is: 



Saint Peter beds /So: 



Jo' | 





»'•"■ -.'••:T-' ■•: j •-... ■■■■" *» 

 I — ■.,.— --_ — ^J :— — 



Fiai re 5, - Classification of the Lower Silv 

 \ cortical section representing the relative thickness of the several b< Is, their lit 1 1 • 

 and their distincl ive faunal types. 



- I l;> 1- 



