re eibe ee’ 
THE GEOLOGICAL SECTION OF MICHIGAN 695 
It looks as though thus close to the Archean land mass the forma- 
tions were much broken by unconformities and sandstones (of course 
allowance must be made for imperfect records), and perhaps the 
term Hermansville will be fittingly applied to the lower 50 feet of the 
Calciferous. We may compare the triple division of the Calciferous, 
with the Shakopee dolomite, New Richmond sandstone, and Oneota 
dolomite of Minnesota. 
tr. St. Peter sandstone-—Outcrops of this have never been identified 
in Michigan. But the Green Bay wells show a constant water- 
bearing horizon at about the level where it should appear, and occa- 
sionally sandstones, or red clays, and residual dolomites. At this 
formation we break the column. It is the top of that part ex- 
clusively known or seen in the Upper Peninsula. It marks a break 
which Rominger and others considered the important break which 
should mark the top of the Cambrian.’ 
t See Berkey, B. G. S. A., Vol., XVII, pp. 229-50. 
