

8o NEW YORK STATE MUSEUM 



is also indicated by the Rysedorph Hill conglomerate, occurring at 

 Bald mountain with its Mohawkian fauna. 



The stratigraphic relation of the Bald Mountain limestone to the 

 shales is nowhere apparent, the observed contacts between the two 

 being along fault planes. Thus the limestone is seen to rest by a 

 westerly rising plane on the folded Snake Hill shales below the 

 falls at Middle Falls ; since the shales are younger than the lime- 

 stone, the latter is here overthrust on the shale. The interbedding 

 of shale between the dolomite and shale, assumed in Walcott's Bald 

 Mountain section, is due to a mass of shale folded or thrust locally 

 into the Bald Mountain limestone. The limestone belt is on one side 

 bounded by the shale, on the other by the Georgian rocks ; and, 

 as a glance at the map will show, it ends abruptly where the edge 

 of the Georgian overthrust blanket southwest of Louse hill turns 

 east, suggesting that this overthrust mass brought the limestone with 

 it (see postea page no). We have thus, principally from the 

 fossil evidence, to assume that the Bald Mountain limestone, which 

 surely is older than the Normanskill shale, overlies the Deep Kill 

 shale. But it may come from an entirely different trough or basin, 

 that originally was east of the Levis trough. 



RYSEDORPH HILL CONGLOMERATE 



Associated with the Bald Mountain limestone in the Bald Moun- 

 tain section and for 2 miles north of it, occurs a conglomerate of 

 striking character. It is best exposed at the north end of the Bald 

 Mountain quarry, and along the brook skirting the north side of the 

 mountain, below the road. The rock consists of a black mud matrix. 

 In it float without assortment pebbles of all sizes, from that of a 

 pea to those 2 to 3 feet in diameter. The smaller pebbles are well 

 rounded, the larger ones subangular with rounded edges. They 

 are in part the Georgian limestone, but also deep blue dolomite 

 and gray and dove limestones. A few of the pebbles have furnished 

 fragmentary fossils which indicate the Trenton age of these pebbles. 

 The fossils were: 



Lingula sp. (fragment) 



Siphonotreta cf. minnesotensis Hall & Clarke 



Rafinesquina sp. (fragment) 



Plectambonites pisum Ruedemann 



Ceraurus cf. pleurexanthemus (Green), fragment 



Bythocypris cylindrica (Hall) 



Isochilina armata Walcott var. pygmaea Ruedemann 



