']2 NEW YORK STATE MUSEUM 



followed by the shales and limestones of the Schodack beds, the 

 whole probably forming an overturned abraded fold. This section 

 would then indicate that the normal sequence is Bomoseen grit, 

 Bomoseen quartzite, Schodack shales and limestone. 



None of the typical roofing slates of the eastern part of the slate 

 belt were observed in the Cambric area, but beds of calcareous 

 quartzite, and especially brecciated limestones observed in connec- 

 tion with the Schodack beds, may represent this division. 



The Schodack beds are especially well seen in the northern 

 Georgian area of the sheet, where the black and gray shales and 

 the interbedded limestones are everywhere exposed along the road 

 skirting the base of the Georgian plateau in the town of Argyle. 

 This area includes the well-known Bald mountain locality, where 

 the black shales are seen with a thin quartzite bed directly above 

 the quarry on the west side, while on the south side the olive grit 

 has been drawn along the fault line into the shales. On the west- 

 ern slope of Bald mountain the thick-bedded, bluish limestones and 

 interbedded dark gray to black partly arenaceous shale of the for- 

 mation are well exposed. 



Walcott, in his monumental monograph of the Cambric Brachio- 

 poda (1912, page 197), records the following species from this 

 neighborhood : 



1 Limestones 1.5 miles (2.4 Km.) north of Bald mountain: 



Obolus prindlei (Walcott) 

 Lingulella granvillensis Walcott 

 Obolella crassa (Hall) 

 Botsfordia caelata (Hall) 

 Acrotreta sagittalis taconica (Walcott) 

 Stenotheca rugosa (Hall) 

 Platyceras primaevum Billings 

 Hyolithellus micans Billings 

 H. micans rugosa Walcott 

 H. communis Billings 

 Elliptocephala asaphoides Emmons 

 Solenopleura tumida Walcott 



2 Shaly limestone on the west slope of the summit of Bald 

 mountain: 



Botsfordia caelata (Hall) 

 Acrotreta emmonsi Walcott 

 Olenellus sp. 



I 



