LIMESTONES OF SOUTHEASTERN MICHIGAN. 11 
fiable fragments secured by Dr C. Rominger, the bed has never yielded fossils until 
during the past season’s work of the State survey. 
The Waterlime beds are much fissured and broken in places, furnishing numer- 
ous localities with underground drainage. Several large and small ‘‘sinks’’ occur 
in the southwestern part of Monroe county, Ottawa lake being the largest. These 
fill up in the spring and then are drained into subterranean channels. At three 
different points live fish are reported to have been pumped from wells, a creditable 
witness assuring me that he saw three mullet-like forms swimming in a pail, hay- 
ing greatly enlarged pectoral fins and being entirely without eyes. 
Calcite and celestite occur in the cavities in the beds at various places, and at 
Maybee these minerals are associated with native sulphur in considerable quantity. 
Above this group of beds lies the Corniferous division of the Upper Helderberg; 
outcropping and artificially exposed at Dundee and Trenton. Just north of the 
latter place the Sibley Quarry Company has opened more than 40 acres to a maxi- 
mum depth of 33 to 35 feet. The main dip of the rocks is west 5 degrees south, and 
equals 2.5 degrees to 3 degrees. Ten beds of limestone, varying in thickness from 
2 to 9 feet, are exposed, and two of chert, 14 and 24 inches respectively. The rock 
is light colored and remarkably rich in lime carbonate, some samples yielding 98 
to 99 per cent. Two drill cores have been taken out, and show that the rock be- 
comes more magnesian as it descends. Fossils are very abundant, particularly 
corals, bryozoa, brachiopods, gasteropods, and lamellibranchs. Fish teeth and 
spines are occasionally found. In the lower strata the rocks are well bedded and 
furnish excellent building stone. The quarry refuse is run through a crusher and 
converted into road material. Burning produces a strong quality of lime, but the 
chief use of the purer beds is in the manufacture of soda ash and caustic soda. 
At Dundee thesame beds are exposed, but are thinner. The rock possesses much 
the same character as at Trenton, contains the same assemblage of fossils, but is 
more highly impregnated with oil. These rocks, known by the present State survey 
as the ‘‘ Dundee limestone,”’ attain a thickness from 100 to 150 feet. Beneath the 
city of Detroit deep borings reveal the presence of three valuable veins of rock-salt, 
struck at depths of about 900, 1,200, and 2,000 feet, the combined thickness of which 
cannot be far from 500 feet. Toward the south these veins approach the surface 
and become thinner, while northward they deepen and thicken. The highest of 
the three veins at Wyandotte gives 50 feet of rock-salt, rapidly thins southward to 
8 feet, and probably gives out completely at Monguagon creek, being replaced by 
eypsum in the wells of Church and Company just north of Trenton. At the latter 
place the second vein in the most northern well shows 33 feet of salt and none in 
the most southern well, so that here seems to be the southern limit of the rock-salt 
along the river, with a possible southwestward extension into Monroe county. At 
both Wyandotte and Trenton the lowest vein isreplaced by gypsum and shale, and 
the Niagara limestone entered at a depth of from 1,250 to 1,400 feet. In the well 
of the Eureka fron and Steel Works at Wyandotte what was believed to be the 
Trenton was reached at 2,610 feet. 
The occurrence of such deposits of solid salt in close association with lime car- 
bonate of as high a grade as that of the Sibley quarry at Trenton is of the greatest 
economic importance to this section of the state. Within less than a decade ten 
millions of outside capital, employing thousands of workmen, have been attracted 
thereby to the banks of the Detroit river. 
Remarks upon the paper were made by HW. W. Claypole, 
