114 NEW YORK STATE MUSEUM 



Guelph dolomite 



This rock, named from its occurrence at Guelph (Ont.) about 75 

 miles northwest of Niagara falls, is, so far as known, absent from 

 the Niagara district. As before noted, it may however be repre- 

 sented in the buried hundred feet of limestone (more or less) which 

 lie above the 130 feet of known rock, as shown by the borings in this 



region. 



Salina beds 



The basal beds of the Upper Siluric are the saliferous shales and 

 calcareous beds of the Salina stage, so named from the salt-produc- 

 ing village of Salina in Onondaga county. This is the horizon 

 which furnishes all the salt, as well as the gypsum of New York 

 state and the adjoining territory. In the Niagara region this forma- 

 tion is not well exposed, owing to the soft character of the 

 rock which has permitted deep erosion in preglacial times, and to 

 the extensive drift deposits which cover it. The only known ex- 

 posures on the Niagara are on Grand island and on the Canadian 

 side of the river opposite North Buffalo. On Grand island the 

 Salina rocks may be seen at Edgewater about 200 yards below the 

 boat landing. Here the following section is exposed. 1 



3 Light colored, soft, friable gypseous shales, 5 feet 

 2 Greenish shales containing nodules of gypsum, 1^ feet 

 1 Black shale in the river bed 



The exposure extends 300 yards down the river bank. 



At the extreme northern end of the island, where it divides the 

 river, an impure, thin bedded limestone of this series is exposed. 

 The exposures on the Canadian bank begin a short distance south 

 of this, and extend to the International bridge, the rock here being 

 a more or less gypsiferous shale. 



From the numerous borings in this region we have however 

 gained a fair knowledge of the character and thickness of this rock, 

 the latter averaging, according to Bishop, 386 feet. The best avail- 

 able record of the rocks lying between the Waterlime and the Ni- 

 agara series of limestones is the core of a well drilled on the land 

 of the Buffalo cement co. in North Buffalo. This core, which has a 

 bishop. 15th an. rep't N. Y. state geologist. 1895. p. 311. 



