76 Tht American Geologist. August, 1894 
and a sixth of a mile in width, is nearly Hat, with a night of 
70 to 75 feet above lake Monona. 
In tin- boiler room of the capitol building a well 1.015 feet 
deep obtains water which rises from its lower portion toGOor 
70 feet below the surface. The section shown by this well is 
boulder-clay from the surface to a depth of eight feet: strat- 
ified sand, enclosing occasional boulders, reaches thence 60 
feet: and gravel occupies the next twelve feet, to a total 
depth of SO feet, where the boring appears to have passed into 
shaly beds of the Potsdam sandstone formation. It is possible, 
however, so far as the record indicates, that the next 46 feet 
also are referable to the drift, being boulder-clay or till. Nu- 
merous other sections on this hill, as for cellars and cisterns, 
pass through the till in five to fifteen feet, coining to sand 
beneath. At 80 feet, or less probably 126 feet, the capitol 
well goes into the Potsdam sandstone, which extends to a 
depth of 805 feet from the surface and is succeeded thence to 
the bottom by Archaean crystalline rocks.* 
The top of the bed rock under the center of the Capitol 
hill, if reached immediately beneath the gravel, lies at a 
greater bight than the beds of lakes Monona and Mehdota, 
the maximum depths of which, according to Prof. E. A.Birge, 
are for the former probably about 50 feet, and for the latter 
75 to 80 feet. The greater part of the area of lake Mendota. 
six miles long and two to four miles wide, seems, by Prof. 
Birge's two transverse series of soundings, to be a rather flat 
tract, depressed 50 to 75 feet below the lake level. Probably 
under these lakes a considerable thickness of drift overlies 
the bed rock, perhaps as much as its average on the surround- 
ing land. 
Northwest of the Capitol hill, an equally long but narrow 
drumlin reaches from the northeast end of East Gilnian street 
west-southwesterly along that street and Langdon street 
nearly to Lake street. At its northeast end this drumlin rises 
with the usual steep slopes, but toward the southwest it is 
prolonged in a very slowly declining ridge. Its top is 85 feet 
above lake Monona. Its surface and the eroded bluff, 20 to 
40 feet high, where its northern side has been worn away by 
lake Mendota. consist of till with plentiful boulders. Prof. 
*Geologj of Wisconsin, vol. ii. 1877, i')>. 50, 605. 
