i8 



Valvata sincera. 



tricarinata. 

 Campeloma decisa. 

 Bifidaria armata (land snail). 



Of mammals the Don Valley brickyard has supplied a 

 bone of a large bear and bones or horns of bison, of a deer 

 like the Virginia red deer, and of a deer related to the 

 caribou. 



Of the trees, seventeen are near their northern limit 

 and scarcely reach Toronto at present, while ten or eleven 

 of the unios and other shell-fish do not now live in lake 

 Ontario, but inhabit Mississippi waters. The whole assem- 

 blage of plants and animals implies a warmer climate than 

 the present, such as that of Ohio or Pennsylvania, as sug- 

 gested by Prof. Penhallow and Mr. White. There could have 

 been no great ice sheet within hundreds of miles of the 

 region when the rich Don forest grew, with its pawpaws, 

 osage oranges and red cedars. 



A walk of half a mile up the Don valley to a second 

 brickyard, just beyond a bend of the river, discloses another 

 section of the Don beds of a somewhat different kind. To 

 the west of the valley Lorraine shale rises 16 feet above 

 the river, followed by boulder clay, on which rests sand 

 with unios like the deposits just described. Two hundred 

 yards to the east the shale can be seen rising eight or ten 

 feet, but between these two points the boulder clay and 

 shale were cut away by an interglacial river, which after- 

 wards began to deposit materials on the shale in the rising 

 waters of a lake. 



At the base of the section there are three or four feet 

 of coarse shingle mixed with matted reeds, leaves and wood. 

 Above this there are eleven feet of sand and clay with many 

 shells. The whole is covered by a few feet of recent sand 

 deposited by the Don before its bed had been cut as low as 

 at present. The trees include red cedar, elm, oak and paw- 

 paw, showing that the climate was warm at the earliest 

 stage of the Don beds. 



If we add these lower beds to the better exposed sec- 

 tion at the Don valley brickyard the total thickness is 40 

 or 45 feet. 



Similar beds of sand and clay containing wood and 

 unios are found at several places along the Don for about 



