56 • NEW YORK STATE MUSEUM 



The Rhinestreet black shale is finely displayed in the walls of the 

 gorge from the top of the north end of High Banks continuously 

 for 8 miles southward to the north end of the St Helena or Gardeau 

 Flats. •! l 



It is the cap rock of the " Hogback " and is finely exposed at 

 Gibsonville, also on Buck run at and above the cascade and in 

 adjacent ravines ; on Cashaqua creek for a mile midway between 

 Sonyea and Tuscarora ; and in the ravine 2 miles northwest of 

 Mount Morris. 



On the east side of the valley it appears in several ravines 1 to 

 3 miles north of Groveland station and in the rock cut of the Dela- 

 ware, Lackawanna and Western Railroad, i l / 2 miles southeast from 

 Groveland station. Very fine fish remains have been collected from 

 this locality. 



The list of fossils contained in the Rhinestreet black shale com- 

 prises the following species : 



Palaeoniscus devonicus Clarke Prioniodus spicatus Hinde 



Pristacanthus vetustus Clarke P. erraticus Hinde 



Acanthodus pristis Clarke Spathiocaris emersoni Clarke 



Polygnathus dubius Hinde Lingula Hgea Hall 



Hatch flags and shale 



In the rather meager description of the " Gardeau flagstones and 

 shales " in the reports on the geology of the fourth district some 

 reference is made to the difference between the character of the 

 lower and upper beds of the division. 



This difference is more manifest in the Naples section specially 

 in regard to the faunas and the horizon of the change is marked by 

 a series of heavy sandstones that have produced an escarpment on 

 Hatch hill 275 feet above the Rhinestreet shale as exposed at the 

 foot of the hill. 



In State Museum bulletin 63, the intervening shales and flags 

 between these sandstones and the Rhinestreet shale were fully 

 described and designated the " Hatch flags and shale." 



In the Genesee section the formation is included between the 

 Rhinestreet black shale and the bank of thin sandstones that is seen 

 in the cliff on the east side of the Gardeau Flats, coming down to 

 60 feet above the river at the east end of the St Helena bridge and 

 to the river level at the mouth of Wolf creek, embracing 209 feet 

 of shales and flags. The shales are in thin layers many of them 

 being black and slaty, others blue and fissile or olive, coarse and 

 sandy. The general aspect of the rock walls in this part of the 



