IMMOBILITY IN THE GEOLOGICAL SCALE. 93 
of this last-named formation. The granite was of the same character 
that is found in the nearest outcrops of Archean rocks—that is, on the 
western boundary of the Adirondack region. The series through which 
the drill descended was normal in every respect. There was found, suc- 
cessively, the Medina sandstones, red and white; the Medina shale, in 
characteristic showing ; the Oswego sandstone and Pulaski shale of the 
Hudson River group; the Utica shale and a series of Ordovician lime- 
stones, 600 feet of which are referred to the Trenton. Below the Tren- 
ton, at a depth of about 100 feet and in accordance with the usual strati- 
graphical sequence of the district, a stratum of white Potsdam sandstone 
was reached. It was 47 feet thick, and a gas vein of fair strength and 
volume was found in it. The gas attained a rock pressure of 340 pounds 
when shut in. 
Immediately below the Potsdam a stratum of dark Cambrian limestone 
was found. It contains rather obscure traces of animal life, apparently 
referable to Cambrian trilobites, and below the limestone, at a total depth 
of about 2,150 feet, the granite was reached, as above described. The 
discovery of gas in the Potsdam sandstone aroused considerable interest 
among the parties in charge, and it was deemed best to try the effect of 
atorpedo on the well. A light shot was lowered, designed for the horizon 
in which the gas was found; but by aslight miscalculation the explosion 
took place somewhat lower than was planned, and, as it proved, in the 
eranite formation in part. A quart or two of granite fragments, some of 
them an inch in diameter, were brought up by the sandpump. ‘The gas 
supply was increased somewhat by the torpedo, but nothing came from 
the well in the way of practical results. But there are certain facts and 
suggestions on the scientific side that are not without interest. 
The gas struck in this well is of Cambrian age. It is thus practically 
coeval with Iingulella, Dicellocephalus, and their allies. It is probably 
the equivalent but altered form of a small stock of petroleum derived 
presumably from the decomposition of Cambrian trilobites and brachio- 
pods. The Cambrian gas belongs, we may be sure, where it is found. 
It is in its original home. There is no source from which it could be 
derived in the granite foundations that underlie, and it cannot have 
come from above. Let alone the constant and insuperable opposition 
of gravitation to its descent through heavier liquids, the shale roof of 
the Potsdam, which proves itself able to withstand a gas pressure of at 
least 340 pounds to the square inch, would have had to be penetrated if 
any supply had come from above. 
No; we have reached at last a point of beginning. There are no 
mysterious depths below on which we may draw in imagination for the 
material from which the petroleum represented by the gas here found, 
XIV—Butz. Grou. Soc. Am., Vou. 9, 1897 
