64 
GEOLOGY OF THE THIRD DISTRICT. 
these singular bodies, as found at Alexander’s bridge below Schenectady, at Normans-kill 
below Albany, and at Hudson city, shows that their origin was vegetable, and not animal, as 
conjectured by some naturalists. Their chemical composition confirms their vegetable nature ; 
no animal ever existing whose material was almost entirely carbon, as is the case with these 
fossils. 
Shales of Pulaski of former reports, the upper division of the Hudson river group. The 
sandstone shale of Pulaski, or fossiliferous portion, is the second or upper division of the 
Hudson river group. As respects its fossil history, it will probably be subdivided, from the 
following facts : 
In the report of 1840, it was said, that “ Fossils are rare in the lower part of the Frankfort 
slate, but are numerous where it joins the next series, the Pulaski shales. To which of these 
two masses they belong, or if they form a separate mass, has not been determined ; but that 
they are important geological lines of division is certain, for there is no essential difference 
between the fossils, whether seen at the mill race at Lee Centre, or Whitall’s quarry near 
Rome, at Hallcck’s spring in Hampton, or the gully near Utica, and the Cohoes near Water¬ 
ford. In all these localities, the group of shells which so peculiarly characterize the Pulaski 
shales are wanting, and others appear that had no previous existence in th£ districtamong 
which is the Dolphin-head trimerus (Trimerus delphinocephalus), the Hampton pentacrinite 
(Pentacrinites hamptonii), and some others which reappear from the Trenton limestone. 
This part or subdivision is uncovered for some extent to the south and west of Rome, and 
occupies the intermediate area to the Frankfort slate proper, and the rocks of Pulaski village, 
separating the two. In mineral character, there is identity between the lower subdivision and 
the Frankfort slate ; whereas the upper or Pulaski part partakes of the same character, and 
of the grey sandstone likewise, thus mineralogically uniting the two. The upper portion 
furnishes some good building stone, the lower none of much consequence. That the separa¬ 
tion into two portions is not accidental, appears evident from the existence of the lower portion 
between the Highlands and Newburgh without the upper portion. 
Sandstone shale of Pulaski, called the Shales of Salmon river, and Pulaski shales; the 
name being changed in order better to express its mineral nature, being a mixture of sand¬ 
stone and shale, the former generally preponderating at the upper, and the latter at the lower 
part of the mass. It is the only rock at Pulaski village in Oswego, and for some distance 
around. It will therefore serve as a type for the name, for with none other can this well- 
defined mass be confounded. 
The fossils by which these shales are readily recognized, are, No. 1 of the wood-cut, the 
Carinate pterinea, (Pterinea carinata); No. 2, Ornate cyrtolite, (Cyrtolites ornatus); No. 3, 
disk of the Hampton pentacrinite, (Pentacrinites hamptonii), from the town of Hampton, 
where first discovered. 
