10 PROCEEDINGS OF THE DETROIT MEETING. 
Remarks were made by G. K. Gilbert, J. W. Spencer, G. F. Wright, 
H. W. Claypole, and the President. 
A second paper by the same author was 
GLACIAL DRAINAGE OF THE SIMCOE AREA IN ONTARIO 
BY F. B. TAYLOR 
Remarks were made by J. W. Spencer. 
The following paper was then read : 
LIMESTONES OF SOUTHEASTERN MICHIGAN, WITH THEIR ASSOCIATED SA ND- 
STONE, SALT, AND GYPSUM 
BY W. H. SHERZER 
[ Abstract] 
Passing in a northeast and southwest direction across the southeastern corner of 
Michigan is a low anticline, which crosses Monroe county and enters Wayne county 
south of Detroit. It is on this anticlinal ridge that most of the natural outcrops 
and quarries occur in this portion of the state. The oldest rocks exposed belong 
to the Waterlime division of the Lower Helderberg, and extend downward, as deter- 
mined by deep borings, into the Salina, which reaches a possible thickness at Detroit 
of 2,000 feet. The Waterlime beds are exposed in the streams and quarries about 
Monroe, and southwestward towards Sylvania, Ohio. These beds consist of a drab 
or brown dolomite, in places brecciated, and characterized by the absence of large 
corals and fish remains. In general fossils are not abundant, and those that are 
found are in the form of moulds and casts. Calcium carbonate comprises from 
54 to 55 per cent of the rock and magnesium carbonate from 42 to 43 per cent. 
These rocks are used locally for building, road-work, and lime. 
A bed of dolomitic odlite may be traced from Stony Point, on the lake Hrie shore, 
southwestward to near the state line. On Plum creek, south of Monroe, this 
bed is 2 feet thick. The granules here are well rounded, but southwestward 
they become in places singularly elongated and almost vermiculate, passing into 
compact dolomite. 
A bed of remarkably pure white sand rock, known by the Ohio survey as the 
Sylvania sandstone, passes northeastward from Sylvania, crosses the Raisin river 
near Grape, outcrops at a point seven miles northwest of Monroe, and curves east- 
ward to the south of Gibraltar. This sand rock is of interest because of its eco- 
nomic value in glass manufacture, because of the secondary enlargement of its 
grains, and because it has been regarded as the equivalent of the Oriskany in this 
region. In Monroe county its thickness seems to range from 20 to 30 feet, but it 
thickens and broadens correspondingly as it passes northward. What seems to be 
the same bed is found at Trenton at a depth of 230 feet; at Wyandotte, 280 feet, 
and at Detroit at 475 feet, it now having attained a thickness of over 100 feet. That 
this bed cannot be regarded as the equivalent of thé Oriskany is shown by the fact 
that it is overlain by beds of Waterlime, consisting of a silicious dolomite, a brown 
sandstone, and a light porous dolomite, exposed at Ottawa lake, Raisinville, May- 
bee, Flat Rock, Gibraltar, and Grosse Isle, With the exception of a few unidenti- 
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