Pleistocene 



the Toronto Formation, gives evidence of an interglacial 

 time far longer than the post-glacial period and with a 

 warmer climate than that of the present. 



The geological succession may be arranged as follows : 



Recent — River and lake Deposits. 



Iroquois Beach Materials. 

 Glacial complex (four beds of till with inter- 

 stratified clay and sand). 

 Toronto Interglacial Formation (Scarboro 



beds, Don beds). 

 Earliest Boulder clay. 

 Palaeozoic — Lorraine shale. 



These will be described in succession from below up^- 

 wards. 



THE) LORRAINE SHAL,E. 



The bed rock of Lorraine shale (Ordovician or Lower 

 Silurian) is generally buried under the drift deposits of the 

 Pleistocene and comes to the surface at comparatively few 

 points and in a quite inconspicuous way. Along the western 

 lake front on Humber bay there are low outcrops rising 

 not more than two or three feet above the water at Exhibi- 

 tion park and west of the Humber river. The shale rises 

 higher along the sides of the river valleys, forming cliffs 

 that reach 30 or 40 feet within the first three or four miles 

 up the Humber, and 10 to 16 feet at the " Bend of the Don," 

 about two miles from the mouth of the river. 



All of these natural outcrops are greatly weathered, as 

 might be expected in so easily attacked a rock as shale, and 

 only the harder limey or sandy layers resist the action of 

 rain and frost. 



Artificial exposures in connection with the brickyards 

 give the best opportunities to study the unweathered rock, 

 the one most easily reached being at th e Don Valley bric jk,- 

 yard, where a great open pit from which shale is~~5eing 

 quarried shows 60 feet of the formation. There are thin 

 seams of impure limestone at frequent intervals in the shale 

 and these have to be selected out before it is crushed for 

 brickmaking. The weathered surfaces of the discarded 

 limestones provide the best fossils in the Don region. The 



