LENGTH OF INTER-GLACIAL TIME 



253 



mated as equal to post-Cllacial time, say 25,UOO years. Tlie deposit of the 

 interglacial beds, checked by the counting of 672 annual layers of clay 

 in a thickness of 19 feet G inches, is considered to have required not less 

 than 4,300 years. The broad, gently sloping interglacial valley of the 

 Dutch church at Scarboro required for its formation a time much greater 

 than the far less mature postglacial valleys. If we say only twice as much, 

 50,000 years. The wliolc of the inter-Glacial interval must liave been 

 75,000 or 100,000 years in length. 



Even if the much too sliort estimate of post-Glacial time given by Pro- 

 fessor Wright — 10,000 years — is employed in computing the length of the 



Section of Don valley; narrow part 



Section of Don valley; wide part 



Level of 



LaHe Ontario 



Section of interglacial valley; Dutch church 



ScaJe of Fee A 



O lOO 



I I — i — 1 — I — I — I— 



/ooo 



l_l 



l''i(:r];i-; ;{. — Si'cliuiix nf iiiti'iiiliuiul iiiiil iKixhjhiiiiit \ itlleijH 



inter-({lacial period, il amounts to 3-1,000 years. From the evidence as 

 to climate given above it can not be denied that as high a temperature 

 existed both at Toronto and on the James Bay slope in inter-Glacial times 

 as now. The Labrador ice-sheet, which centered only 300 miles northeast 

 of tlic James Bay lignite deposits, docs not exist now and could not exist 

 in the equally warm or j)robably warmer inter-Glacial time. If the great- 

 est of all the ice-sheets, that of Labrador, was melted in the earliest inter- 

 Glacial j)rrii>d. what iiic the probabilities in I'egai'd to ihe smalK-r ice-shee! 

 fore.st growth ;it least us i-icli as the |ii'c<cnl on the west sitU" of James 

 Bay? Tt seems higidy improbable tliiil the Keewatin ice coidd survixe a 



