40 GEOLOGY OF THE THIRD DISTRICT. 



This remarkable and eminently characteristic fossil is extremely abundant along the Mo- 

 hawk. The most satisfactory locality for obtaining specimens of it, is at the quarry on the 

 side of the river opposite Lower St. Johnsville, just above the ferry house. It is there replaced 

 by lamellar carbonate of lime ; and so gradual was the substitution of this mineral for its 

 original material, and so favorable has been the action of weather and water, that the external 

 form and internal structure are completely exhibited. The whole plant, or polypous animal, 

 be it which it may, is composed of quadrangular cells more or less regular, arranged in groups 

 from eight to sixteen in number. The form of the cells or openings at the surface or upper 

 extremity of the fossil, when not broken, is somewhat circular, and gives to that part a fanci- 

 ful appearance. These groups of cells are connected laterally with each other, by a more or 

 less angular anastomose. This singular and interesting fossil, though so abundant in this 

 limestone as before remarked, has not been found above it, nor below it. 



The birdseye Umestone is confined to the counties of Montgomery, Herkimer, Oneida and 

 Lewis. Li goin^ west, on the south side of the Mohawk, it first makes its appearance at 

 the village of Fort-Plain. It is there upon the calciferous, under which are the fucoidal lay- 

 ers, the Trenton limestone covering its surface as before mentioned. The rock is about ten 

 feet thick, and it has been fractured in two places, causing one part to be a little lower than 

 the other. It was wrought for the enlarged Erie canal. It shows exudations of hydrate of 

 iron where fractured. 



The next point west is Smith's quarry : it is a httle to the south of the river road, and to 

 the southeast of St. Johnsville. The quality of the stone of this quarry is much better than 

 that of the one to the south of St. Johnsville ; but there is not so much rock exposed, nor is its 

 connection with the other rocks so obvious. 



The quarry back of the ferry opposite St. Johnsville, is the third locality on the south side 

 of the river. Besides the fucoids already noticed, the rock here contains cytherinae in con- 

 siderable numbers. I found also fragments of a trilobite, which appears to be new ; a few 

 tentaculites, and an orthocera not before noticed. 



The layers in this quarry are much disturbed, and have furnished but little good stone ; 

 owing to the surface of the calciferous, which forms the floor of the quarry, being disposed in 

 flat dome-shaped forms, to which the layers of the birdseye have conformed ; it is not over 

 six feet in thickness. On the south side of the quarry, the thin irregular layers of the Tren- 

 ton limestone cover it as at Fort-Plain. 



At Manheim ferry, the birdseye again is seen just opposite to the mouth of East Canada 

 creek : also at the top of the uplift on the south side of Little-Falls ; at the brook on the west 

 side, near the old saw mill ; and at the extensive quarry of Mr. Parmlee, about two and a 

 half miles west of Little-Falls ; just beyond which, it finally disappears under the water of the 

 canal and its overlying rocks. The quarry is opened for some distance, and the layers are 

 very regular, excepting where a few short low curvatures exist : their position in the quarry 

 is nearly horizontal ; the vertical joints straight, even, and wall-like. Fossils are rare : those 



seen were Fucoides demissus, Orthoceras , and a ramose polyparia found between two of 



the layers of the rock. An immense quantity of stone has been taken from this quarry, for 



