316 C. SCHUCHERT MEDINA AND CATARACT FORMATIONS 



Green and gray, impure, calcareous shale, with the same fossils as 

 above. Thickness about 11 feet. 



Bluish gray calcareo-arenaceous shale, 11 feet. 



Concealed area, 7 feet. 



Buff shales, with thin beds of fossiliferous magnesian limestone, 12 

 feet. Helopora fragilis, Rhinopora veri'ucosa, Platystrophia Mforata, 

 Leptcena rhoml)oidali», Ccelospira planoconvexa. 



Bluish gray and green shales, with thin bed of magnesian fossiliferous 

 limestone, 8 feet. Fossils same as those below. 

 Manitoulin member. Dark bluish gray magnesian limestones and shale 

 weathering a pale red, 7 feet. The most fossiliferous horizon and 

 the type locality for Coelospira planoconvexa. Also here Helopora 

 fragilis, Pachydictija crassa, Phwnopora ensiformis, Rhinopora ver- 

 rucosa, RhipidomeUa circulus, Orthis ftahellites, Hehertella fausta, 

 Leptwna rhomdoidalis, Platystrophia Mforata, Atrypa rugosa, Whit- 

 fieldella naviformis (this identification very doubtful), Cornulites 

 distans, Modiolopsis (?) orthonota, Encrinurus cf. punctatus, etc. 



Gray, compact, calcareous sandstone in two beds, 21 inches thick. Za- 

 phrentis, Helopora fragilis, Pachydictya crassa, Phwnopora ensiformis, 

 Leptcena rhomhoidalis, Dalmanella elegantula, Camarotwchia neglecta, 

 Ccelospira planoconvexa, and Cornulites distans. 



Gray, thin-bedded, shaly sandstones with greenish shale partings, Cwlo- 

 spira planoconrvxa, Modiolopsis (?) orthonota. 

 Whirlpool sandstone mcmhcr. Basal gray, heavy-bedded sandstones, 8.5 

 feet thick. 

 Disconformity. Base of Siluric. 



Queenston. Top of Ordovicic (Richmondian). According to the Dundas 

 artesian well the thickness is estimated at 535 feet. 



Limeliouse, Ontario, section (25 miles north of Dimdas). — On cucsta 

 cut by Grand Trunk Railway, 3 miles west of Georgetown, Ontario. 



Lockport bluish gray, heavy-bedded, cavernous dolomite, with much frag- 

 mental organic material. Quarried for lime burning. Thickness 

 present 20 feet. The lowest 2 to 4 inches consists of a basal con- 

 glomerate made up of small and weathered (yellow) Clinton lime- 

 stone pebbles in a muddy dolomite. The regular Lockport dolomite 

 appears at about 6 inches above the Clinton. In the basal beds 

 occur many heads and tails of a large Illcenus (near 1. ioxus) piled 

 upon one another like saucers. Also HalysUes with large corallites 

 in loose chains. 



Disconformity. Ko Rochester here. Contact sharp between adjacent beds. 

 [Grabau as censor holds that all of the Rochester here and elsewhere 

 is changed in character to that of the Lockport, and therefore that 

 there is no break. Likewise for the next disconformity, where all of 

 the Medina is said to be changed into the Cataract facies. The -writer 

 does not subscribe to these conclusions.] 



Clinton thin-bedded, gray to greenish (weathering yellowish to white), and 

 more or less impure limestone (sometimes called a water-lime, but 

 not used for lime). Thickness 6.5 feet. 



