The Maquoketa Shales. — James. 341 
ately beneath which comes the Galena limestone. Thus at 
this point the shales have increased to nearly three times their 
thickness at Savannah, and have sunk 388 feet beneath the 
surface, showing a dip of over nine feet to the mile. 
In 1887 Dr. George M. Dawson published"' some details of a 
l)oring at Rosenfeld Station on a branch of the Canadian 
Pacific railway, in the Red River valley, Manitoba. In this 
l)oring the Maquoketa series has an estimated thickness of 
three hundred and fifty two feet, and consists of grey and red 
shales, sandstones and limestones. Dr. Dawson correlates the 
beds represented in this boring with rocks of the same age in 
Minnesota and Wisconsin. He gives, also, on the authority 
of Mr. J. H. Panton details of a section at Stony mountain, 
Manitoba, of rocks for a depth of one hundred and sixty feet. 
These were pronounced from the fossils, examined by Mr. J. 
F. Whiteaves to be of Hudson River age. These rocks are 
supposed to represent the lower two hundred and sixty feet of 
the rocks of the Rosenfeld well. It would apj^ear from this 
correlation, that after thinning out very materially toward 
Minnesota, the shales increase again in thickness to the north- 
ward. It may be doubted, however, whether they extend un- 
brokenly across Minnesota to its northern boundry. 
In 1888 professor S. Calvin noted"^ the formations passed 
through in a deep boring made at Washington, Iowa. He here 
records that at a depth of 702 feet from the surface there Avas 
found a "fine bluish or greenish shale, identical in all respects 
with shales of the Hudson River group, as seen in the blufls 
at and below Bellevue, Iowa. Clay shales, sometimes with an 
admixture of sand, and again with some calcareous matter, 
are continued down to a depth of 793 feet. This group of 
shales are plainly referable to the Hudson River shales of 
Hall or the Maquoketa shales of White." 
This locality is some 75 miles south of the typical locality 
of the shales. The drift was 350 feet in thickness, which 
makes the top of the group 353 feet below the rock surface, 
and we thus have a dip of about 4| feet to the mile, and an es- 
timated thickness of the rocks of 91 feet. It would thus ap- 
pear that they thin out very materially toward the south as 
well as toward the north. 
'"Trans, and Proc. Roy. Soc. Canada, vol. 4, sec. 4, pp. 8G-8"J. 
"* American Geologist vol. 1. pp. 28-31. 
