412 



REPORT OF NATIONAL MUSEUM, 1904. 



In this report, too, he first announced that the upper Mississippi 

 country north of the Wisconsin River was based upon magnesian lime- 

 stones which were older than the lowest formations of the valley of 



%. /. 



Ten, a 

 ar > Jo^itiferous Strata 



"-yfi-^s ZatT 



-fossiiifcrous, unstratificd rrx-ks 



Unstratified rocks 



Primary fosailif crous S 



-Protozoic Rocks 



Fi s .4. 



'•> f*~$T~^<' rS***^— ~~— < ' -> — — r- r ' " ~~~ s Coal Mt asur e S 



^^^^S&5^^^t 



Fig. 46. — Owen's geological sections. 



the Ohio, a portion of them being contemporaneous with the Calcif- 

 erous group and Potsdam sandstone of New York. He noted also 

 that the Fulls of St, Anthony are receding and were probably at one 

 time at a point near Fort Snelling. 



