OF THE NEW-YORK SYSTEM. 
51 
As my object now is merely to state very brielly the order of succession of the lower 
New-York rocks, I have only to say, that from the Calciferous sandrock upwards, there is 
a series of limestones described in the New-York Reports as Cliazy, Birdseye and Trenton 
limestones; all of which, together with the black marble of Isle La Motte, are largely 
formed in Northeastern New-York. It appears, also, according to Dr. Troost, that the 
same limestones are found in East Tennessee, with the same fossils; a fact of great inte¬ 
rest, as it sustains the position assumed in the Report of the Second District, namely, that 
the Chazy rocks are not simply local interpolations, but may be considered as well defined 
general masses. 
Still proceeding upward in the New-York series, we now have reached those slates and 
shales which have been denominated the Utica slates , and Hudson-river or Pulaski shales. 
The first is really a black calcareous shale. The succeeding mass is more or less sandy, 
and finally terminates in a thick-bedded sandstone interlaminated with a dark-colored 
slate. The whole thickness in New-York, at the termination of the Helderberg range 
towards the Mohawk valley, is not far from seven hundred feet. 
I have no occasion to extend this descriptive list of the lower rocks of the New-York 
system farther. The succession is clear and unequivocal, determined directly by super¬ 
position ; a superposition which may be at once seen by any one who will travel across 
Jefferson county from north to south. The Potsdam sandstone is here the inferior mass : 
it gradually passes into the Calciferous sandstone; and in both rocks there is a species of 
Lingula , either identical or so closely allied as to be distinguished with difficulty. The 
bearing of this fact will be stated more fully hereafter. I may, however, say in this place, 
that it entirely dissipates the notion advanced by Prof. Rogers, that the Potsdam sandstone 
of the New-York system and the granular quartz of the Taconic system form one identical 
rock. 
The lower rocks, those now under consideration, are the only ones which, either in this 
country or Europe, have ever been termed the Metamorphic rocks , or have ever been con¬ 
founded with those that I have called the Taconic rocks or system. Some of them are 
unquestionably equivalent to the Caradoc sandstones of the Silurian system. The Medina 
sandstone, which succeeds the Hudson river rocks (black and grey shales and a thick-bedded 
sandstone, with the Utica conglomerate at the superior part), is no where found in the 
vicinity of the Hudson river ; but here they are immediately succeeded by the thin greenish 
and reddish shales, which finally pass into the thin-bedded limestones called in the New- 
York reports the Manlius water-limes. 
Having stated very succinctly the order of the lower palaeozoic rocks of the New-York 
system, I deem it unnecessary to follow up the succession, inasmuch as there is scarcely 
a possibility of confounding the Helderberg division with the Taconic system, and inas¬ 
much too as it is admitted by all who dissent from my views in regard to this system, that 
it is the lower division only which is metamorphosed into that long belt of slates, shales, 
crystalline limestones and sandstones lying between the Hudson river on the west and 
7* 
