1891. ] FAIRCHILD—SECTION OF STRATA AT ROCHESTER. 185 
Howell, however, was inclined to regard these as proper Trenton, and 
considered that which I have marked Calciferous as partly Birdseye 
and Chazy. 
The last two samples are the most doubtful. The drillers declare 
that they worked thirty-six hours to cut the short distance represented 
by the last sample, and that the resistance of the rock surpassed any 
previous experience. This sample is a very fine ferruginous quartz, 
mostly angular fragments, and represents either a crushed red sandrock, 
a siliceous conglomerate or a ferruginous quartzite. The small pro- 
portion of rounded grains might, perhaps, have been ‘derived from the 
stratum above, sample 63. The fineness of the material would indicate 
that the rock was of extreme hardness, and that the drill expended its 
energy in pulverizing the material, like a pestle in a mortar, instead of 
penetrating the rock. It is doubtful if any rock except metamorphic 
would so resist the drill. No material except quartz has been observed 
after careful study. Other minerals might have been removed by the 
water. The iron color seems to be largely superficial. 
The probability of this representing the Archean or the Algonkian 
is reasonable, as at the nearest exposures the Calciferous lies directly 
upon crystalline rock. 
By aid of published and manuscript records, chiefly of Mr. C. S. 
Prosser, it is possible to make some interesting comparisons of the 
thickness of the rocks in this and near localities. Sections to the 
westward are available from St. Catharines, Canada, eighty-two miles 
from Rochester, and Gasport, N. Y., fifty miles from Rochester; to the 
eastward, from Clyde, forty-two miles from Rochester, and Wolcott, a 
few miles northeast of Clyde. 
THICKNESS OF MEDINA. 
Red Medina alone. 
St. Catharines.” Gasport.* —- Rochester. Wolcott. Clyde. 
850 SS 1075 690 942 
Medina, including the transition strata Oneida or Oswego. 
St. Catharines. Gasport. Rochester. Wolcott. Clyde. 
850 1056 1158 1070 1034 
THICKNESS OF HUDSON AND UTICA. 
St. Catharines. Gasport. Rochester. Wolcott. 
785 640 598 650 
1. The thickness of the Devonian and Silurian rocks a7 Western Central New Vork, by 
Charles S. Prosser, in AMERIGAN GEOLOGIST, Vo!. 6, October, 1890. 
2. Ashburner, in Trans. Am. Inst. of Min., Ergrs., Vol. XVIII., 1890, p. 300. 
3. For the record of the Gasport well the writer is¢indebted to Mr. Prosser, also to Mr. C. V. 
Messler of Gaspo-t. 
