34 



2. Lower Lowville (Beatricea beds). — The red and 



green shales pass upward into impure magnesian limestones, 

 which on fresh fracture are greenish-grey in colour and 

 weather yellowish brown. They are characterized by 

 numbers of drusy cavities, occasional quartz grains and 

 crystals of pyrite or limonite, and are generally barren of 

 fossils. They are only a few feet in thickness and are 

 followed by 6 to io feet (i.8 to 3 m ) of fossiliferous blue- 

 grey to dove-coloured limestone characterized by an 

 abundance of a species of Beatricea. These beds somewhat 

 resemble in physical character the typical fine-grained 

 "Birdseye" limestone, but are less compact in texture 

 and weather to a shaly mass. These beds contain a con- 

 siderable fauna, among which may be mentioned : Rafin- 

 esquina minnesotensis , Zygospira recurvirostris, Cyrtodonta 

 huronensis, Lophospira bicincta, Isotelus gigas and Tetra- 

 dium halysitoides. They are overlain by 7 to 10 feet 

 (2-1 to 3 m.) of unfossiliferous magnesian limestone very 

 similar to the beds which immediately underlie them, 



3. Upper Lowville (Birdseye) limestone. — The 

 Beatricea beds are overlain by about 20 feet (6 m.) of 

 fine-grained, even-bedded, dove-coloured limestone, char- 

 acterized by such fossils as Phytopsis tubulosum, Bathyurus 

 extans, Leperditia fabulites, and in the upper portion 

 by a great abundance of Tetradium cellulosum. 



The Lowville limestone, which is sometimes included 

 in the Black River as a sub-formation, is well developed 

 in south central Ontario, and is remarkable for its constant 

 lithological and faunal character not only throughout this 

 district, but a; far as Kentucky, Tennessee and Alabama 

 on the south. 



BIBLIOGRAPHY. 



1. Goldthwait, J. W An instrumental Survey of the 



Shore lines of the extinct Lakes 

 Algonquin and Nipissing in South- 

 western Ontario. Geol. Survey, 

 Can., Memoir No. 10. 



2. Logan, Sir Wm. E... Geology of Canada: Report of 



Progress of Canada. Geol. Survey 

 to 1863, pp. 983. 



