o 



No. 3.] SPENCER — PALEOZOIC GEOLOGY. 135 



Beds. Medina Formation. Thickness. 



No. Feet. 



4 Bluish sandstones in two beds, splitting in slabs 2.7 



3 Coarse sandstone — the Gray Band — varying much in 

 thickness. This is separated from the beds above 

 by shaly parting 7.3 



2 Medina shales — green, red, or variegated — partly 

 covered here, but various portions exposed in many 

 places 141 . 



1 Ked, green, and variegated shales (measured in Arte- 

 sian Well) 394.0 



545.0 



Total thickness 800 . 



Section II. (at Dundas). 



This section was measured partly along the Sydenham road, and 

 partly in the glen just west of it. The measurements are in 

 descending order, and the numbers of the beds refer to the equi- 

 valent beds in Section I. 



Niagara Formation. 



Cherty dolomites, forming brow of escarpment along 

 13 Sydenham road. The upper portion in the section 



6 represented at the "Peak," by more than 100 feet, 

 12 being removed by denudation for some distance 



back of the brow 19.0 



1 1 Dolomitic shales 0.8 



10 Compact gray dolomite, more or less argillo-arenace- 



ous, in beds from 2 to 2.5 feet thick 14.0 



9 h Shaly dolomites 4.5 



9 a Dolomitic shales 6.0 



8 Compact gray dolomite in one bed, highly crystal- 

 line, with cavities filled with minerals 5.5 



7 Gray dolomite, more or less argillaceous 10.0 



59.8 



Clinton Formation. 



6 Clinton shales, with thin beds of areno-argillaceous 



A dolomites, sometimes ferruginous, some of the beds 



5 are fossiliferous. About 20 feet from the top there 

 is a bed of red ferruginous, calcareo-arenaoeous 

 sandstone, rich in casts of fossils 85.7 



85.7 



Medina Formation. 



4 Bluish sandstone splitting into thin slabs 2.1 



Shaly parting 0.8 



3 Coarse gray sandstone — the " Gray Band " — varying 



in thickness from 6.7 to 9 feet 8.1 



See below, 



2&1 Medina variegated shales (as calculated) 535 . 



546.0 



Total thickness 691 . 5 



