330 REPORT— 1900. 



since provided evidence favouring the interglacial age of the sands. At 

 the sewer stratified sand, evidently a continuation of the deposits just 

 mentioned, contains clayey sheets with thin bands of peaty material con- 

 taining remains of beetles, mosses, seeds, plates of mica, &c., precisely like 

 the peat from the cold climate series of Scarborough and the Don 

 valley. Since these peaty layers are probably equivalent in age to the 

 peaty clays east of the city, we may suppose that the sandy deposits of 

 the western part of Toronto are also interglacial, in the upper part evi- 

 dently belonging to the cold climate series, but perhaps representing the 

 warm climate deposits at lower levels. It is clear that the conditions in 

 Western Toronto must have been different from those to the east, 

 since here a great thickness of stratified sand replaces stratified clay. 

 This may be explained by supposing that an interglacial Humber river 

 brought from the west sand and gravel into the great lake then occu- 

 pying the Ontario Valley to mingle with the clayey delta materials of the 

 interglacial Laurentian river flowing from Georgian Bay to Scarborough. 



Just beneath a thin sheet of till in the Dupont Street sewer the upper 

 end of the ulna of a mammoth or mastodon was found, the bone having 

 been polished and scratched by glacial action, suggesting that it lay on 

 the surface when the ice advanced for the last time. Some pieces of wood 

 occurred near by, but lower down in the section. 



We may now sum up the results obtained by the Committee and 

 former investigators of the Toronto formation, so as to show the series of 

 events recorded, the thickness of the deposits, and the fossils obtained from 

 them. 



In most places the Toronto formation is found to overlie a bed of cha- 

 racteristic boulder clay containing rocks brought from long distances to 

 the north or north-east, and covering the eroded surface of the Cambro- 

 silurian rocks of the region. This boulder clay probably belongs to the 

 lowan till sheet of the United States. After the retreat of the ice there 

 was an interval of erosion shown near Shaw Street, and in the interglacial 

 i-iver valley at the bend of the Don ; followed by the deposit of clay, sand, 

 and gravel containing trees and unios of a warmer climate than the 

 present, the greatest thickness amounting to thirty-three feet in the Don 

 valley, and to thirty-five feet below Lake Ontario at Scarborough. 



These beds have nowhere been found at a higher level than fifty feet 

 above Lake Ontario, and the upper sands and gravels were probably laid 

 down in shallow water, since they are browned and sometimes cemented 

 with oxide of iron. 



Conformably upon the warm climate beds are a series of beds 

 containing trees and other fossils, especially beetles, suggesting a cooler 

 climate than the present ; not Arctic, however, but cold temperate. 

 These are best shown at Scarborough Heights, where stratified peaty 

 clays starting a few feet below the level of Lake Ontario have a thickness 

 of ninety-five feet, followed by fifty-five feet of stratified sand. It is pro- 

 bable that part at least of the seventy feet of sand found in the western 

 part of Toronto is of the same age. The interglacial lake at this stage 

 must have stood at least 150 feet higher than Lake Ontario. 



A long period of erosion followed the draining of this lake, during 

 which river valleys a mile or more in width were cut through the delta 

 deposits at Scarborough to the depth of more than 1 50 feet comparable to 

 those cut by the Don and Humber since the Glacial period. 



Finally a fresh advance of the ice, probably belonging to the Wisconsio 



