BIGSBY — PALAEOZOIC ROCKS OF NEW YORK. 355 



Section V. 



Three miles south of Utica. It commences below the quartzose sandstone No. 2 

 of the last section (not seen here), and consequently is 60 to 100 feet below 

 the top of the group. 



f 1. Hard siliceous and silico-calcareous layers alternating; with much Feet, 

 marine vegetation 15 



2. A slope, probably shaly 20 



3. Shales and shaly sandstones, with Buthotrephis, Beyrichia, &c, 

 and iron beds 



4. Upper portion shaly, and the lower part of thin-bedded sand- 

 stones with wave-lines and ripple-marks ; Beyrichia, Nucula, 

 marine plants 15 



5. A slope, probably shales 25 



6. Alternating layers of shaly sandstones, sandstone, and conglome- 

 rate with shale 28 



a 

 o 

 u 



a 



S3 1 



O 

 -^ 



S3 

 •J 



U 



103 

 7. Oneida Conglomerate. 



We see, then, that in the eastern and central parts of New York, 

 the Clinton group is capped by a thick mass of sandstone, red or 

 grey, accompanied by green shale ; and that, among many minor 

 changes, as we travel westward, limestone in single or more layers, 

 a few feet thick, gradually creeps in from near Lockport, which 

 are in two bands at Rochester, thicken greatly at Medina, and at 

 Lewiston constitute almost the whole group. 



The Clinton group in the centre of New York is a powerful and 

 ever-varying formation. Its analogies there are chiefly with the 

 Medina Sandstone ; but in its western extension the Clinton group 

 assimilates to the Niagara group, becoming in mineral and fossil 

 aspects truly Wenlock, and quite distinct from itself in Oneida 

 County*. 



Vanuxem, in his Report, p. 83, gives some account of the ore-beds 

 at Sodus ; and which are characteristic of this group as far west as 

 the Genesee River (Hall, Pal. ii. 15). He calls them beds of lenti- 

 cular clay-iron-ore (like the fossiliferous iron-ore of Pennsylvania), 



* Professor H. D. Rogers defines the Clinton group, as it occurs in Pennsyl- 

 vania, in the following terms : — 

 It consists of three parts. 



1. The upper ; variegated red marls or calcareous shales. 



2. The middle ; an alternation of shales and argillaceous and fossiliferous 

 limestones and calcareous sandstones, with one or two remarkable seams of fos- 

 siliferous iron- ore. 



3. The lower group, consisting of greenish and yellowish fissile slates, wea- 

 thering olive- and claret-coloured, including in their central parts beds of red, very 

 ponderous, ferruginous sandstone, usually containing two or three thin layers, 

 rich enough in peroxide of iron to be available as an iron-ore. 



The Professor goes on truly to say that the northern outcrop of Clinton, in 

 ranging towards the west, displays what many other formations exhibit — a gradual 

 change from a shore to a mid-sea type, — the shales and sandstones becoming gra- 

 dually less in volume, and the limestone relatively augmenting. A bed of lime- 

 stone and another of calcareous shale are all that represent it on the Niagara 

 River ; and in Wisconsin it is composed of little more than a thin stratum of 

 fossiliferous limestone, which is there in contact with the Niagara Limestone, and 

 with which it has been confounded. 



