64 GEOLOGY OF THE THIRD DISTRICT. 



these singular bodies, as found at Alexander's bridge below Schenectady, at Normans-kill 

 below AlbanVi 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 Pidaski, 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 tlie fossils, whether seen at the mill race at Lee Centre, or Whitall's quarry near 

 Rome, at Halleck's spring in Hampton, or the gully near Utica, and the Cohoes near Water- 

 ford. In all tliese localities, the group of shells which so peculiarly characterize the Pulaski 

 shales are wanting, and others appear that had no previous existence in the district ;" among 

 which is the Dolphin-head trimerus (Trimerus delphinoccphalus), 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 tovra of Hampton, 

 where first discovered. 



