296 
[Assembly 
The shale in some places appears to be composed entirely «f small 
fragments of organized remains, and towards the upper part of the mass 
is a stratum composed of a species of Orthis, so numerous and so close- 
ly compressed that the form and outline of the shell is nearly obliterat- 
ed. The points where this shale can be seen are, south of McAllister's 
quarry, along the east and west road on lot 26, and about two miles 
and a half south of Waterloo; at this place it contains Posidonia and a 
few other fossils, besides numerous small fragments. 
II. Dark slaty fossiliferous shale^ in Varick and the southern part of 
Fayette, and of Flint creek. Mud creek, &c. in Ontario county. The 
upper part of the last described shale becomes very fissile and crumbles 
rapidly on exposure to the weather. From this it passes into a dark co- 
loured or black slaty shale, readily separating into thin irregular la- 
minos. Nodules or concretions of limestone are scattered at distant in- 
tervals, and never disposed in regular courses. The fossils, both in the 
contained limestone and in the rock, are entirely different from those in 
the mass below, being an Orthis deeply striated or grooved, and in the 
shale very much compressed; and a flattened spiral univalve. At many 
points fossils are exceedingly rare, and the mass, on slight examination, 
might be mistaken for a non-fossiliferous one. 
This shale is exposed along the shore of Seneca lake for several miles 
above the outlet, and in ravines across the county. On the Cayuga 
lake it is well developed along Sinclair's creek near Mr. Wicker's, and 
in a ravine one mile farther south; also along the lake shore. 
III. Compact calcareous blue shale. The shale last mentioned gradu- 
ates into a bluish, more compact and less slaty, calcareous shale; which, 
in the upper part, approaches in character a blue limestone. Some por- 
tions of this mass are sufficiently pure tor burning into lime. The two 
masses together attain a thickness of more than one hundred feet, and 
the whole is characterized by fossils peculiar to itself. One or two spe- 
cies of Pterinea occur below the more compact portions associated with 
Cyrtoceras, Orthoceras, a large Delthyris, Leptasna, &c. The Delthy- 
ris w^ith a long striated spiral univalve, are found in the more calcareous 
portions. 
This part of the series is easily recognized near Tyler's tavern, on the 
Seneca lake shore, ten miles from Geneva; also on the ravines on Cay- 
uga lake, near Mr. Wicker's, where its projecting edges produce beau- 
tiful and picturesque falls. Its great hardness protects the softer shales 
both above and below, from the rapid destruction which the streams 
