650 NEW YORK STATE MUSEUM 



break the Decker Ferry fauna listed by Weller, 1 the Manlius, 

 with a magnificent cystid fauna, among which is Camarocrinus 

 in great abundance, followed by the typical Helderbergian and 

 Oriskanian. The respective faunas of these formations may be 

 gathered in the vicinity of Cumberland and southward for a 

 hundred miles or more into the Virginias. Continuing in this 

 direction, overlap causes the lower formations to wedge out one 

 after another till, finally, only a little of the Helderbergian and 

 Oriskanian series is represented in the Sneedville or Handcock 

 limestone of southwestern Virginia and northeastern Tennessee. 

 Northward from Cumberland, through Pennsylvania and New 

 Jersey into New York, the lower formations pinch out in the 

 same manner as in the south, so that in the Kittatinny valley 

 of New Jersey it is practically the Decker Ferry formation only 

 that rests on the " red and white Medina " or Shawangunk. 

 From here north, however, the Decker Ferry, Manlius and Hel- 

 derberg formations continue in full force to near the Mohawk 

 river, presenting thus a condition differing widely from that 

 obtaining in the southern end of the basin. It is in this north- 

 ern area that one finds the extensive and readily accessible 

 Helderbergian deposits that furnished the fauna so well de- 

 scribed and beautifully illustrated by Hall. For this reason, 

 and because the subsidence appears to have been continuous, 

 we have chosen the name Helderbergian for the invasion. In the 



other cases of movements named by us, we have taken the name 



i i 



1 Geol. sur. of New Jersey for 1899. 1900. p. 7-21. Some of these identi- 

 fications are admittedly provisional and require verification, Mr Weller 

 having followed Hall's correlation of the Coralline limestone as the eastern 

 representative of the western Niagara, an obvious error now that we know 

 that the Coralline limestone lies just below the Rondout, at Rondout N. Y. 

 However, the typical Rondout should not be confounded with the Water- 

 lime of Buffalo N. Y. The Rondout formation is but the base of the Man- 

 lius, and the former is completely transitional downward into the Coral- 

 line limestone. The Helderbergian invasion in New York begins with the 

 Coralline, while the Cayugan emergence closes with the so called " Clin- 

 ton " of the Schoharie section, which we consider the overlapping eastern 

 edge of the Salina deposits, and certainly not equivalent to the true 

 Clinton. 



