LOWER SILURIAN SYSTEM OE EASTERN MONTGOMERY CO. 439 



G"- Massive, thick bedded, very fine grained^ 

 drab limestone with smooth nearly vertical joint 

 faces. Weathers light bluish gray to ash-white. 

 Fracture conchoidal. Birdseye limestone. 4"=4' 



From no. 5 of the above section the following species were col- 

 lected from the thin layers which are stripped from the upper part of 

 the quarry. 



1 Rafinesquina alternata (Con.) Hall and Clarke (a)^ 



2 Orthis (Dinorthis) pectinella (Emm.) (c) 



3 Orthis (Dalmanella) testudinaria Dal. (c) 



4 Plectambonites sericea (Sowerby) Hall (c) 



5 Zygospira recurvirostra Hall (r) 



6 Rhynchotrema capax (Con.) Hall and Clarke? (r) 



7 Asaphus platycephalus Stokes . ♦ (r) 



8 Leperditia fabulites (Con.) (r) 



9 Monticulipora (Prasopora) lycoperdon Say (r) 



10 Schizocrinus nodosus Hall (a) 



1 1 Stictopora acuta Hall (r) 



No. I of this section undoubtedly belongs to the Birdseye horizon, 

 nos. 2 and 3 to the Black river and nos. 4 and 5 to the Trenton. 

 The lower layers of the upper quarry can not be far above the upper 

 layers of the lower quarry if they are at all above them. The speci- 

 mens of Orthis pectinella found in the upper quarry are 

 the clearest specimens of that species obtained from any exposures 

 in this region and the species is also more abundant here than else- 

 where. In fact I have not seen the species in abundance anywhere 

 in the Mohawk valley except here and at the Cook quarry north of 

 Littlefalls. Some of the specimens of Rafinesquina alter- 

 nata are very gibbous and have the radiating striae subequal and 

 the concentric striae prominent and crowded. 



North of this quarry are many exposures of the Trenton stage 

 about Rockton. Slightly northeast of Rockton the Trenton lime- 

 stones disappear and the Calciferous comes out in force toward 

 Hagaman. 



In the eastern part of Amsterdam the Calciferous sandrock is ex- 

 posed in the south slope of the hill below the cemetery at an altitude 



^Relative abundance of species is indicated as follows: a, abundant; aa, very abun- 

 dant; c, common; cc, very common; r, rare; tt, very rare, where only a single specimen 

 is found. 



