60 F. T. THWAITES 
As No. 1 of the section does not contain fossils, the correlation 
of this section with that seen in the sand pit to the east is somewhat 
puzzling, but the evidence of the rocks and fossils, of the sloping 
surface of the Lower Magnesian seen in the sandstone pit, and a 
close study of the supposed fault unite in definitely proving that 
the St. Peter pinches out in the interval. Statements of Mr. 
Kroll regarding exposures formerly visible in a trench through the 
quarry floor also confirm this explanation. Similar phenomena 
without the complicating presence of folding are known elsewhere 
in the vicinity.’ 
Fic. 4.—Close-up view of gravel seam, showing weathering of adjacent dolomite. 
(Photograph by W. O. Hotchkiss.) 
Before considering the origin of the gravel seam, the question 
of the origin of the fold with which it is related may be considered. 
The fold might be due: 
1. In some way to the pinching out of the St. Peter. 
2. To glacial pressure on the east side of the hill, which forced 
up the wedge of St. Peter sandstone resting upon the sloping 
surface of the Lower Magnesian. 
3. To the same processes which formed the major joints and 
the other faults and minor folds which are found in the Paleozoic 
rocks of eastern Wisconsin. 
«T. C. Chamberlin, Geology of Wisconsin, Vol. II (1877), pp. 270-75. 
