No. 275.1 313 
The mass of encrinal limestone, which has already been mentioned 
as dividing the upper mass of shale from that next below, occurs in 
great perfection along this lake. Large masses have been transported 
to the foot, and lie along the beach and in the wall which protects the 
road from the actign of the water. Some of the these boulders contain 
few or no encrinal columns, but their other characteristics refer them to 
this formation. 
Along Mud creek the shales may be seen at various localities, and in 
all the large ravines; but in the smaller ones their decomposition has 
formed a soil which in many cases conceal the rock. In the western 
part of Ontario, and particularly west of Mud creek, the alluvial hills 
have covered the underlying rocks as far south as the extent of these 
shales; while in other counties the southern limit of the high alluvial 
hills is generally, except in valleys, the limestone range before describ- 
ed. 
The Tully limestone I have observed but at two points in Ontario 
county; one in the bed of Flint creek at Bethel, and only visible when 
the water is low; the other four miles northwest of that village, near 
the main road and about a mile from the north line of the town of Gor- 
ham; there it consists of a single layer three feet thick, and exhibits the 
characteristics of that rock. This point is on the elevated land between 
Flint creek and Canandaigua lake; the surface slopes in either direction 
towards the valleys, which are valleys of denudation. These produce 
very irregular lines of outcrop. 
West of the point last named, I have not seen this limestone, al- 
though its place in the shale is well defined for many miles along Ca- 
nandaigua lake. 
The line of distinction between the lower shale and the black shale 
succeeding the Tully limestone, is w^ell defined as far west as the Ge- 
nesee valley. It occupies the southern part of the town of Seneca, and 
appears in some places in the more elevated parts; and in Gorham ex- 
tends several miles north along the high ridge between Flint creek and 
Canandaigua lake West of Canandaigua lake this shale spreads out 
over a much greater extent of country, passing through the towns of 
Cheshire, Bristol and Richmond, and becomes fossiliferous in all its 
parts. It appears on Mud creek and in the ravines and streams about 
the outlet of Honeyoye lake. The burning springs, so called, of Bris- 
tol, proceed from the carburetted hydrogen, arising from this shale; the 
numerous localities will be mentioned in another place. 
fAssem. No. 275.] 40 
