30 Calvin on the ^Deep Well at Washington, Iowa. 
The Trenton limestone with its ordinary lithological charac- 
ters in the Northwest continues down, as shown by the borings, 
to a depth of 1059 feet. At 1082 feet is a bed of sandstone, 
and from 10S4 to 1095 feet is an arenaceous shale, both of which 
probably belong to the Trenton series. 
From 1100 to 1200 feet the borings show the usual charac- 
teristics of the St. Peter's sandstone. Some of the specimens 
are pure white, granular, resembling refined sugar. Others are 
brownish or reddish, stained with metallic oxides. At 1145 
feet, the sand when taken out was pure white, but owing to the 
combined action of the atmosphere and moisture it has since 
changed to a bright red. The change is most marked at the 
sides of the bottle, the sand in the middle retaining nearly its 
original color. 
At 122S feet is a thin bed of bluish shale that I am inclined 
to think represents the Lower Magnesian limestone. This can 
be better determined after the boring has progressed somewhat 
farther. If the conclusion is correct, then a grayish sand 
marked 1230 feet represents the upper part of the Potsdam 
series.' 
The geological horizons that may be determined with a great 
degree of certainty are the Hamilton, Hudson River, Trenton 
and St. Peter. A noticeable fact and one of great interest is 
the absence of dolomytes. In place of the dolomytes of the Ni- 
agra period we seem to have 100 feet of sandstones. The place 
of the buff or cream-colored, coarse, granular Galena limestone 
seems to be filled with a grayish limestone not dolomitic. Fi- 
nally, if my conclusion regarding the shale at 1228 feet be cor- 
rect, we have the Lower Magnesian limestone reiDresented by a 
bed of clay. While the deposits of the Lower Magnesian 
limestones were going forward in northeastern Iowa, the place 
now occupied by Washington, Iowa, was more remote from 
the then-existing shore line, and was more deeply submerged 
than any point at which we now find these limestones exposed. 
The same may be said with reference to the other dolomitic 
formations. Can it be that dolomyte is only formed near the 
shore? The Hudson River shales, the Trenton limestone and 
' Prof. Calvin here probably means to indicate the upper part of the 
St. Croix formation of the Mississippi valley. — N. H. W. 
