50 GEOLOGY OF THE THIRD DISTRICT. 



layers, tougli and solid, is a highly durable and valuable building material, as well as a good 

 marble for finer work. 



There arc but few kinds of fossil shells associated with the grey variety, nor are the indi- 

 viduals usually numerous. The Little-eared delthyris (U. microptera), and the Deltoid 

 delthyris are those usually met with, besides fragments of cncrinal stems. 



It is evident from a slight examination of the geological map of Montgomery, that the Utica 

 slate once extended from the primary to the river, covering the whole of the trenton and 

 the calciferous group of the county, the three masses being originally coextensive with each 

 otlier. From uplifts and denudation, more than half of the slate has been removed from the 

 surface of that part of the county, and the whole also of the Trenton limestone beneath, with 

 the exception of a few insulated partial masses or patches. These masses occur in Broad- 

 albin, Mayfield, Amsterdam, Tripes hill, to tlie east of Fonda, to the north of Epliratah 

 village, to the southwest of that village also, east by north of Fort-Plain, the creek at Pala- 

 tine church, and Crumb creek. It may be necessary to state, however, that in this number 

 a few are included which are still in connection with the slate. 



From tlie fact of the Calciferous group, the Trenton limestone and the Utica slate being 

 coextensive with each other, it is obvious, that on the south side of the calciferous, and on its 

 west side where it joins the Utica slate, in consequence of the uplift being from east to west, 

 the Trenton limestone will also there be found, as well as the two intervening ones, the base 

 of the trenton and the birdscye, should such have been deposited, these latter rocks not exist- 

 ing coextensively with the others ; a fact which may yet be of some practical consequence to 

 those parts of the country. 



The quarries and other localities to the south of the calciferous, and south of the Mohawk 

 river, are illustrative of the fact, and show us where to seek for the masses between the cal- 

 ciferous group and the slate. The two first are those of Port-Jackson, and Sage & Reed's, 

 both of which belong to the base of the trenton ; the Trenton limestone proper is only seen 

 in small quantity at the latter locality, from the little space yet uncovered. 



The first of the Trenton limestone proper that was seen going west, of any thickness of 

 note, is at the Noses, resting immediately upon the Calciferous group, which is well observed 

 at the falls of the creek back of Spraker's basin ; also at the dam of Canajoharie creek ; at 

 Fort-Plain, on both sides of the creek ; at the quarry opposite to St. Johnsville ; at Manheim 

 ferry ; in Herkimer county, at the top of the uplift, south of the river and village of Little- 

 Falls ; and at Parmlee's quarry to the west of the falls, being the terminal part of its range. 

 The localities enumerated are but the points where the rock is exposed along its most 

 southern line in the district ; the intermediate ones being covered with soil and other loose 

 materials, the limestone existing coextensively with the lower rock, on the south sides of the 

 uplifts, where the river has cut its passage through them. 



On the west sides of the uplifts, where the calciferous is exposed over such large surfaces, 

 it was seen but in a few places, being covered by alluvion and soil, and no particular exami- 

 nation having been made for it. That it must exist there, is certain, from its continuousness 



