NORTHERN END OF THE HELDERBERG PLATEAU 57 



Feet 



stone, gives a thickness of 3475 feet for the Hud- 

 son river and Utica formations at this locality. 

 Along the small brook in which the gas well is 

 located there are exposures of the Hudson river 

 formation, consisting of bluish to grayish argil- 

 laceous shales, with an occasional sandstone 

 stratum; but the upper part of the zone is 

 covered around the slope of High point. 

 C 2 In places at the base of the cliff 1 to 1J feet of 1=647 



dark gray, impure, thin bedded limestone is ex- 

 posed, which resembles the upper layers of the 

 waterlime at Schoharie and Howe's cave, to 

 which formation it is referred. 

 <C 3 The lower part of the cliff is composed mainly 38=685 

 of thin bedded, dark blue limestones, having the 

 metallic ring of those composing the Tentaculite 

 formation, and in the lower part are abundant 

 specimens of Tentaculites gyracan- 

 t h u s (Eaton) Hall. By the side of the High 

 point path there is 38 feet of this rather thin 

 bedded limestone, in all of which Spirifer 

 vanuxemi Hall is common, even to the top. 

 The Tentaculites was not found in these 

 upper layers. At this horizon there is a litho- 

 logic change; the upper beds are more massive, 

 breaking with an irregular fracture, and 

 Pentamerus (Sieberella) galeatus 

 (Dal.) Hall occurs near their base, so that the 

 line of division between the Tentaculite and 

 Pentamerus limestones was considered to be 

 represented here. The following species were 

 collected at this place. 

 1 Tentaculites gyracanthus (Eaton) Hall (aa) 



"2 Spirifer vanuxemi Hall (a) 



-3 Leperditia alta (Con.) Hall (r) 



4 Modiolopsis dubius Hall (rr) 



