113 



GEOLOGY OF THE THIRD DISTRICT. 



mottled very impure limestone, somewhat resembling the one at its base. The same fossil 

 also exists in the upper layer of the group, at the quarry south of Chittenango, &c. 



This group is readily recognized by its fossils, in every part of the State where it exists, 

 and in Pennsylvania also ; but beyond these two States, it has not yet been recognized. 



The wood-cut below exhibits six of the fossils of this group ; some of which, such as Nos. 

 1, 3 and 6, are extremely abundant, and Nos. 1 to 5 have only been found in this group. 



23. 



No. 1. Plicated orthi» (O. plieaU). 



2. Rugous avirula (A. ragosa). 



3. Ornated tentaculites (T. omotua). 



No. 4. Antique littorina (L. antiqua). 



5. Sulcated atrypa (A, sulcata). 



6. Elevated cytherina (C. alta). 



These are but a few of the different kinds of fossils which were found in this group ; but 

 from the frequent, nay almost constant association of Nos. 1, 2 and 6, it was readily recog- 

 nized by these three alone. Among the others not figured, it may be well to mention that 

 some localities abound in a strophomena which appears to be peculiar to the group ; that it 

 was also the only position in the district where a catenipora, probably the labyrinthica of 

 Goldfuss, was found ; and that it contains also an agnostis, which may be the piciformis, or 

 Pea-shaped agnostis ; the details of all which fossils are left for the report upon that subject. 



The water-lime group is one of those coextensive with the Helderberg range. Throughout 

 its range in the district, it contains the drab layers which constitute the water-lime proper ; 

 but no water-lime is made to the east of Madison county, as before mentioned. To the east, 

 the drab-colored portions sure fossiliferous ; rarely, even in parts, so pure ; their color of a 

 darker yellow by alteration, often brownish ; and they appear evidently to have been formed 

 under somewhat different circumstances from those which appear to correspond with them to 

 the west. The layer also which is so much used through Madison, Onondaga and Cayuga, 

 to make common lime, is obscure to the east of the above named counties. 



Localities. The group appears by the road-side, ascending the Helderberg range to Cherry- 

 Valley from Fort-Plain, showing the dark blue layers with numerous specimens of Plicated 

 orthis, cytherina; and also tentaculites. The light-coloured and more impure layers appear at 

 a lower level, in the ravine or gully to the right of the road. The first or lowest portion con- 

 sists of irregular layers, with Globuliform columnaria ; above which there is a drab-colored 

 series, followed by the upper blue or dark-colored ones. 



The group forms the head of the falls near Judd's mill, to the left of the road, and north of 

 the village of Cherry- Valley. 



