78 Geological Survey of the State of New York. 



when we consider the obscurity and confusion that have pre- 

 vailed concerning these formations, and the impediments that ex- 

 isted to a proper understanding of them, not to partake of the 

 enthusiasm of the palasontologist, as he approaches the conclusion 

 of his labors, and the gratification he expresses that '' the legisla- 

 ture of New York has had the liberality to cause the organic re- 

 mains of the various formations to be figured and described in 

 the final report of the geologists. The plan contemplated in 

 describing them, is that of a stratagraphical, or grouping of all 

 the organic remains in a particular series of strata, referable to 

 one geological epoch ; and a student may, with the book be- 

 fore him in the field, identify at once the rocks he desires to in- 

 vestigate." 



" The series in New York is far more complete than that of 

 Wales described by Murchison, the formations pre-eminently 

 characterized by their organic contents being three times the 

 number of those illustrated in the Silurian System." 



The comparison of the two series has resulted in identifying 

 the " Trenton limestone''' with the " Caradoc sandsto7ie" the 

 Llandeilo flags not being represented here, — showing the impor- 

 tance of organic remains, in the absence of lithological resem- 

 blance. 



The " Salmon river sandstones and shales," possess a distinct 

 and peculiar group of fossils, and are not represented in the Silu- 

 rian System. The "Niagara sandstone" contains fossil remains 

 peculiar to it, and is characterized in New York, Pennsylvania 

 and Virginia, by the splendid Fucoides Harlani. Although this is 

 not found in Wales, " some of the fossils in the strata above it are 

 characteristic of the upper parts of the Caradoc sandstone ;" and 

 all these Mr. Conrad considers its equivalent. " The Wenlock 

 shale is identical with the shales at Rochester, which abound in 

 the Asaphus limulurus of Green, (A. longicaudatus, Murch.)" 



" The Wenlock hmestone immediately succeeds the Wenlock 

 shale in Wales, but the two formations are here separated by 

 the following rocks, each of considerable thickness, and with 

 distinct fossil groups. 1. Lockport limestone. 2. Gypseous 

 shales. 3. Water lime series. Over the latter we find a blue 

 sub-crystalline limestone, and then a gray shaly limestone, which 

 together appear to represent the Wenlock formation, both in fos- 

 sils and mineral character." 



