1847.] Geology of Lewis County. 315 



by crystalinc carbonate of lime, it being the Birdseye limestone 

 proper of geologists. 



Occasionally the fossil here mentioned is replaced by fibrous 

 spar, which exhibits upon the weathered surface of the rock a 

 very beautiful appearance. Examples of this may be seen in 

 Carter's quarry, near the village of Lowville. 



No material could be more suitable than this for building; and 

 in some localities it is so symmetrically divided by natural joints, 

 as to need little or no labor to prepare it for the wall. 



Where these joints do not occurr, it is observed to have a pe- 

 culiar tendency to break into rectangular masses. The strata of 

 this division are generally of uniform thickness, and vary from 

 four to twelve inches. 



The upper division of the rocks which form the first terrace of 

 limestone in the county, is composed of a thick bedded rock, sepa- 

 rated into large masses by natuial seams, which are often widened 

 into fissures by the action of the elements, and is constantly as- 

 sociated with hornstone, which occurs disseminated in nodules 

 throughout its substance, and which seem to have been separated 

 from the rock by segregation, before it had become solid. 



This thick bedded stratum forms every where the surface mass 

 of the first terrace, and streams of water frequently disappear, and 

 are lost in its fissures, uniformly reappearing at the junction of 

 this with the impervious birdseye limerock below it. In several 

 places the waiter has worn caverns of limited extent in the rock, 

 examples of which may be seen on Roaring Brook, in Martins- 

 burgh. Fossils are not numerous in this rock, and are, from its 

 compactness, very difl^icult to extract. They however occur beau- 

 tifully exposed, where the rock has been weathered, standing out 

 in relief from the surface. Among the genera that have been ob- 

 served, are, Orthoceratites, Columnaria, Orthis, Strophomena, and 

 a Cyathophyllura, with its surface covered with minute concentric 

 circles. 



Owing to the lumpy texture of this rock, and its want of uni- 

 formity in composition, it is wholly unfit for any useful purpose. 

 It may be observed advantageously near Lowville village, on 

 Roaring brook, Sugar river, and in short, most of the streams that 

 flow into the river from the west. 



From the situation of this rock, between the Birdseye and the 

 Trenton limestones, its fossil contents and thickness of strata, I 

 have no hesitation in' pronouncing it the " Isle La Motte Marble" 

 of the New-York Reports; and identical with the Black marble 

 of Glen's Falls, and the " Seven foot tier" of Watertown. The 

 thickness of the stratum in Lewis county is about eight or nine 

 feet, and appears to be quite uniform, wherever observed. 



The strata of the Birdseye and the thick bedded masses above 



