PALEOZOIC ROCKS FOUND IN DEEP WELLS 555 



Michigan shore as far north as Sheboygan, Wisconsin. Deep wells 

 in this belt are reported to find a red sandstone below the light- 

 colored Cambrian, suggesting that possibly a Keweenawan sand- 

 stone fills the Michigan trough as one does the Lake Superior 

 syncline. It is well established that the Keweenawan red sand- 

 stones of Lake Superior extend southwest into Minnesota below the 

 Cambrian.^ Few samples have been obtained from these rocks 

 since, on account of the poor water which they yield, wells are 

 no longer drilled deep enough to reach them. 



' C. W. Hall, O. E. Meinzer, and M. L. Fuller, " Geology and Underground Waters 

 of Southeastern Minnesota," U.S. Geol. Survey Water Supply Paper 256, (191 1), pp. 

 32, 48. F. T. Thwaites, "Sandstones of the Wisconsin Coast of Lake Superior," 

 Wisconsin Geol. and Nat. Hist. Survey Bull. 25, (191 2), pp. 58-61. 



