GLACIAL AND INTERGLACIAL BEDS 299 



and from a higher elevation, where at present some trees found 

 in the Don valley are wanting, such as Platanus occidentalis, 

 which reaches its northern limit at Toronto. 



The peaty clay occupies the western part of the great bay 

 into which the Laurentian river emptied when the intergla- 

 cial lake was at its greatest height. It appears first at Rosebank, 

 16 miles east of the Don, and is last seen with certainty 2^ miles 

 west of the river in a sewer on Bathurst street, making a width 

 of 18^ miles. Dr. Hinde reports it also from the mouth of 

 the Humber, 6 or 7 miles west of the Don, but the writer has not 

 been able to find it there, though somewhat loesslike sandy silt 

 containing a few plant remains, occurring near the Humber, 

 may represent the peaty clay of Scarboro'. If so, the whole 

 extent of the beds will be 25 miles from east to west. The last 

 exposure known towards the north is 6y^ miles inland from Lake 

 Ontario, and no doubt if the cuttings of the Don were deep 

 enough it would be found considerably farther north. The 

 greatest thickness of the clay at Scarboro' is about 94 feet, 5 

 below the lake and 89 above ; but the upper limit is rather hard 

 to fix, since it becomes interbedded with sand. Toward the west 

 the peaty clay rises higher, reaching 150 feet north of Reservoir 

 Park and in the Bathurst street sewer. 



INTERGLACIAL SANDS 



Above the peaty clay at Scarboro' there are stratified sands 

 with a thickness of 55 or 60 feet where best developed near the 

 central part of the heights, following the lower beds conformably 

 and apparently laid down in shallower water but under similar 

 climatic conditions. The lower 4 or 5 feet have clayey layers, 

 but above this the sand is quite coarse, through free from peb- 

 bles, and shows cross bedding in some layers. In the sand are 

 found all the usual minerals of Archean rocks, and a few bands 

 of garnet and magnetite occur, evidently arranged under wave 

 action, as on the present beach at the foot of the cliff. Just over 

 the peaty clay there is sometimes an accumulation of coarse 

 woody material, flattened twigs, bits of bark, etc., with quite large 



