St. Peter's Sandstone. 



accompanying the report, the sandstone is represented as " F. 

 2? c," and as occupying a position beneath the lower shell 

 limestone, and above the Lower Magnesian limestone. 



In 1852, Dr. D. D. Owen* described the St. Peter's sand- 

 stone in almost the identical language used in the report of 

 1848, referred to above. 



Having in this brief historical review given an account of 

 the observations made upon the rocks previous to its receiv- 

 ing the name which it now bears, let us examine the forma- 

 tion somewhat more minutely as to its distribution, lithologi- 

 cal characters, stratigraphic position and fossils. 



DISTRIBUTION. 



The St. Peter's sandstone is confined to a limited district in 

 the upper Mississippi valley. It is found in the States of 

 Minnesota, Wisconsin, Illinois, Iowa and Missouri, and possi- 

 bly in the northern peninsula of Michigan. 



In Minnesota it outcrops in an irregular line in the south- 

 eastern part of the State, extending north-west from the 

 southern boundary to above Minneapolis, and south-west 

 again to Martin and Jackson counties. 



In Wisconsin it is found in a narrow strip running from 

 the Menominee River, at the north-eastern boundary, to the 

 southern boundary, occurring in patches wherever the rivers 

 have cut into the superincumbent formations to a depth 

 sufficient to reach it. It also outcrops to a limited extent in 

 St. Croix and Pierce counties in the north-western corner. 



In Illinois it is found in two isolated patches ; one of these 

 is on Rock River, near Grand de Tour ; the other on the 

 Illinois River, in La Salle County. It also probably under- 

 lies a part of the State, being only known by deep -well 

 borings. 



In Iowa it is found exposed only in the north-east corner, 

 though its presence has been revealed in other localities by 

 deep wells at from 1,100 to 1,200 feet beneath the surface. 



:: [Protozoic rocks in the northwest. J Geol. Survey Wisconsin, Iowa and Minne- 

 sota ; and incidentally of" a portion of Nebraska Territory. Philadelphia, 1852, pp. 

 69-71. 



