315 



A dolomite bed 12 to 16 inches thick. 

 Sandy shale zone 2 to 10 inches thick. 

 Whirlpool sandstone memher. Basal greenish gray sandstone in one bed 

 10 feet thick. 

 Disconformity. Base of Siluric. 



Queenston. Brick-red sandy shales. Exposed for about 250 feet. No fossils. 

 Top of Ordovicic (Richmondian). 



Dundas, Ontario, section (5 miles northtvest of Hamilton). — On 

 cuesta and gulch back of the town about one mile in and around the 

 large quarries. See Logan, Geology of Canada, 1863, pages 313-314 and 

 325-326; and Spencer, Canadian Naturalist, vol. 10, 1883, pages 6-7. 



Lockport dolomite. Present 37 to 169 feet. The contact with the Rochester 

 is not easy to make out here. The basal few inches of the Lock- 

 port, however, have a conglomerate of shale pebbles, but there is far 

 less of sand and pyrite than at Hamilton. The Lockport at this 

 place begins with the Gasport crinoidal magnesian limestone. 



Disconformity. Nearly all of the Rochester is absent. 



Rochester formation. Thickness about 6 to 7 feet. Seen to best advantage 

 at the waterfall in the steep gulch. Here these dark calcareo- 

 arenaceous shales are hard to distinguish from the overlying Lock- 

 port, but elsewhere under the influence of weathering they break 

 up into shaly material, as the Lockport never does. Fossils scarce. 

 Billings reports Rhynchonella (?) rohusta, Spirifer radiatus, Meri- 

 stina naviformis, Atrypa reticularis, etc. 



Clinton limestone. Contact sharp with Rochester. Thickness about 14 feet. 

 This formation has here about the same characters as at Hamilton. 

 The Irondequoit member has a thickness of 5.5 feet and the Wolcott 

 member of about 8.5 feet. The basal layer of the Clinton is replete 

 with glauconite and there is also much sand in the dolomite. Eight- 

 een inches above the base occurs an abundance of Pentamerus ol)- 

 longus (Clinton form), and 6 Inches higher occur Favosites niaga- 

 rensis and F. favosus. 



Disconformity. Contact sharp between adjacent beds. Section broken here. 



Medina sandstone. Thickness apparently not over 8 feet. At the top are 

 evenly bedded thin sandstones for about 5 feet, then green shales 

 with some sandstones, and at the base 2 feet of sandstones. No 

 mud-ball formation seen here. Contact with the Cataract below also 

 sharp. 



Cataract formation. Thickness about 94 feet (Logan). 



Cal)ots Head shale member. Green shales with interbedded thin mag- 

 nesian limestones, 6 feet. 



[The rest of the section is taken from Logan.] 

 Red ferruginous shale and shaly limestones, 7 feet. 

 Red, ferruginous, impure, thin-bedded limestones, abounding in fossils, 

 7 feet thick. Helopora fragilis, Rhinopora verrucosa, Phcenopora ex- 

 planata, Leptwna rhomhoidalis, Camarotoschia neglecta, Pterinea (f) 

 primigenia. 

 Red marly shale (4 feet), green shale (2), and red, calcareous, thin- 

 bedded sandstones (1). Thickness 7 feet. • 



