356 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



and says that they lie in the red laminated sandstone, separated from 

 the Oneida Conglomerate only hy some shale and white sandstone 

 with pebbles. 



There are two ore-beds, 20 feet apart, and each 12 to 15 inches 

 thick. The ore in all its localities is red or brownish-red, very hard, 

 invariably oolitic, or in larger-sized concretions, — the oolitic particles 

 being more abundant in the lower bed, the other in the upper. 



In the "fourth geological district" they are separated by the calca- 

 reous shale, which contains the Pentamerus dblongus abundantly. 

 This fossil, however, is rare in the east of New York (Vanuxem's 

 third district), but is constant, from its first appearance in the east, 

 as far west as beyond Monro County. 



Transition. — Everywhere in the eastern and central parts of the 

 State this group rests upon Oneida Conglomerate ; for there is no 

 Medina Sandstone in those districts. We have a good superposition 

 east of Saltspringville, where we have, in succession from below — 1 . 

 Frankfort Slates; 2. Oneida Conglomerate; and 3. The Clinton group. 

 (Hall). 



Further west, however, this group rests upon Medina Sandstone, 

 as the sections given above make manifest, — the change being from 

 quartz to clay, and apparently abrupt. 



Thickness. — It is thickest in the centre of the State ; but how 

 thick exactly, I have not learnt. At Canojoharie it is only 50 feet 

 thick ; near Utica it exceeds 1 00 feet. 



Position. — Being usually remote from causes of disturbance, the 

 dip of this group follows that of the adjacent strata, and is almost 

 horizontal, any inclination being toward the west and south. 



Fossils. — A great outburst takes place in this group, of both 

 animal and vegetable life ; and this certainly from the great variety 

 of mineral habitats which it presents. In the east, in the centre of 

 the State, and on its western frontiers, invertebrate existence differs 

 almost altogether. 



One hundred and thirty-one new existences appear. These arise 

 chiefly among the Plantae, Zoophyta, Bryozoa, Brachiopoda, and 

 Cephalopoda. It receives only 10 forms from the older strata, as 

 may be seen in the Table of Escaped Fossils (IV.). It transmits 28 

 to the newer strata, 8 of these being Brachiopoda. 



In the west the Clinton group loses many of its own characteristic 

 fossils, and becomes charged with the Wenlock types of the Niagara 

 group, — the limits of the two not being always very readily dis- 

 cernible. We have, nevertheless, a good guide as to the real birth- 

 place of the fossils which hover about the limits of these two important 

 and closely-connected groups, in the fact, that on the Clinton side of 

 the probable limit the Clinton fossils are well-formed, while those 

 of Niagara are ill-developed (Hall). 



Tracks of molluscs, crustaceans, and other animals are common 

 in this group, but they will be spoken of more conveniently after- 

 wards. 



The sandstones of the Clinton give us 13 typical species of plants 

 in Eastern and Central New York especially. Scarcely one is seen 



