244 A. p. COLEMAN THE EARLIEST INTER-GLACIAL PERIOD 



is much the most important in thickness of the deposits and in the 

 great amount of fossil materials which have been obtained from it. The 

 lowest of the four interglacial beds only will be considered here. It is 

 intended to show that the time interval was very much longer than post- 

 Glacial time, and that the removal of the ice was very widespread, in- 

 cluding a recession beyond the James Bay slope toward the north. It 

 is probable that the Toronto inter-Glacial period is the same as the 

 Aftonian. 



The Toronto formation includes two divisions — a lower one, best shown 

 at the Don Valley brickyard, which may be called the Don stage, and an 

 upper one, best seen at Scarboro Heights, the Scarboro stage. There is 

 no unconformity between the two ; but the fossils of the Don indicate a 

 warmer climate than the present, while tiiose of Scarboro suggest a some- 

 what cooler climate than the present. However, the fossils of the Scar- 

 boro beds are not arctic nor subarctic, as might be supposed, but tem- 

 perate forms. All of the living species represented in the beds are now 

 inhabitants of southern Ontario. Of the larger number of extinct beetles 

 little can be said with certainty as to climate. The change of climate 

 within the time of deposit of the interglacial beds was distinct, but not 

 extreme. 



The Don beds will be taken up first. 



The Don Beds 



The preglacial surface at Toronto had a somewhat high relief and 

 was made up, so far as known, of weathered Lorraine shale, more or less 

 carved into river valleys. The oncoming ice swept otf the weathered ma- 

 terial, mixing it with solid blocks of shale and limestone, as well as the 

 varieties of Archean rocks which occur to the north. Granites, green- 

 stones, and green schists are common, and also well polished and striated 

 blocks of solid Trenton limestone and smaller fragments of black Utica 

 shale. No rocks of later formations than the Lorraine have been found, 

 so that the ice must have advanced from the east or northeast. If it had 

 come from the northwest or west, one should find fragments of the Red 

 Medina sandstones or shales or of the Clinton or Magara or Guelph 

 limestones, all easily recognized rocks; but none have been found. There 

 should also be blocks of the jasper conglomerate and the red quartzite of 

 the Huronian region, which likewise have never been fouiul, though tiio 

 lowest boulder-clay has been carefully studied at more than one point. 

 The first ice-sheet came, therefore, from the Labrador center, 700 miles 



