﻿1 8 NEW YORK STATE MUSEUM 



and now in the other, remaining throughout an area of small 

 subsidence. 



The deposits laid down in this depression are of upper Stones 

 River age and the name of Pamelia limestone is proposed for 

 this New York phase of the formation. Locally it is known as 

 the " blue limestone " though the local name commonly includes 

 the overlying Lowville limestone as well. A thin, basal sand- 

 stone appears, after which follow alternating black, blue and 

 gray limestone beds, then the black limestone disappears and 

 white, earthy limestone alternates with_the others. During the 

 deposit of this upper portion the waters seem to have become 

 shut off from the open sea, by the development of some shoal or 

 reef as a barrier, and in the lagoon thus formed water lime was 

 deposited, the waters often evaporating sufficiently to expose 

 wide mud flats which dried and cracked under the sun's influence. 

 The marine fauna found these conditions uncongenial and disap- 

 peared, though returning from time to time for a brief space with 

 fresh influx of water from the sea outside. Deposition became 

 intermittent and eventually ceased and some slight wear oc- 

 curred locally. 



Lowville, Watertown and Trenton limestones. Subsidence 

 then recommenced, and upon this slightly worn Pamelia surface 

 the dove-colored limestones of the Lowville formation were laid 

 down. The Lowville submergence was somewhat more exten- 

 sive than the Pamelia, since the former appears in the Mohawk 

 valley while the latter does not. And though both formations 

 occur along' the Black river valley it seems probable that the 

 Lowville sea encroached more widely upon the borders of the land 

 which lay to the eastward. 



The Lowville is a quite pure limestone for the most part, and 

 carries a much more abundant and varied marine fauna than do 

 any of the older rocks. Above it lies a more massive, cherty lime- 

 stone, separated from the main mass of the Lowville by an un- 

 conformity, which we are calling the Leray limestone, and classing 

 as an upper member of the Lowville. Above this, also with an 

 unconformity between, comes a similar massive limestone, without 

 chert, which we are proposing to call the Watertown limestone. 

 The Watertown and Leray limestones taken together are known in 

 the region as the Black River limestone, the Leray being locally 

 more like the Watertown than like the Lowville in character. Be- 

 cause of this, and because of their small thickness (about 10 feet 

 each), we have felt constrained to map them together. They carry 



