136 The American Geologist. 
Maicli, 1900 
Mohawk A'allcy has already been described by Prof. Brig- 
ham.* Then tlie well entered the lower part of the Utica shale, 
passing through 280 feet of this formation. Apparently 105 
feet of Trenton limestone was found, and at least 20 feet of the 
Birdeseye limestone. The samples from 580 and 600 feet are of 
this sub-formation, and if it continued to the samples from 
630 feet then the Birdseye is 50 feet thick. The sample 
from 630 is clearly in the Calciferous sandrock, which appar- 
ently continued to 1 105, which would give a thickness of 475 
for the Calciferous sandrock. It is a little difficult to decide 
precisely where the Laurentian gneiss began ; but it is appar- 
ently at 1,105 ^t., in which case the well entered the gneiss to a 
depth of 30 feet. 
Samples of the drillings from a depth of 1,116 and 1,133 feet 
were submitted to Dr. A. C. Gill, of Cornell University, who 
wrote me as follows : 
"I have examined the samples and find that they are doubtless frag- 
ments of a hornblende-gneiss. The one from 11 16 seems to be less fresh 
than 1 1 33, and a little more acid. Both contain large quantities of mag- 
netite, and 1 1 16 has some rusty spots which I have not investigated, but 
which 1 think are pyrite or pyrrhotite weathered since the boring."! 
Gas was not obtained in commercial quantities, but it was 
found in small amount at three horizons in the Calciferous 
sandrock, at depths of 800, 950, and 1,003 ^^^t, which are 
respectively 170, 320, and 373 feet below the top of the for- 
ination. 
The thickness of the Trenton and Calciferous formations, 
as determined from this well, is somewhat greater than in the 
measured section at Little Falls, 10 miles E. N. E. The Cal- 
ciferous formation at Little Falls, as measured by Mr. Cum- 
ings and myself, is 452 feet in thickness, ;|: while in the Ilion well 
it is at least 475 and possibly nearly 500 feet thick. The 
Birdseye and Trenton limestones have a thickness of loy feet 
at Little Falls, while in the Ilion they are at least 125 and pos- 
sibly 155 feet thick. At the bottom of the Trenton there is at 
least 20 feet of limestone, which has the lithologic character of 
the Birdseye, and a part of the 30 feet between the last sample 
*Bull. Geol. Soc. Amer., vol. q, 1898, p. 188. 
tLetter of Jan. 5, 1898. 
J 15th Ann. Kept. State Geologist [New York], 1898, pp. 634, 635. 
