TOKONTO ISLAND 477 



justments to the present water level. Both the Eouge and the Humber 

 have also excavated larger and broader valleys than the Don, and in prac- 

 tically the same kinds of material, but have built no appreciable deltas at 

 their discharges. It must, however, be remembered that in distributing 

 stream waste which is discharged into the lake the waves will distribute a 

 considerable portion, consisting largely of the coarser debris along the 

 shores ; a smaller portion of the coarse material and almost all of the fine 

 will be carried out and deposited in deeper water. Waste deposited below 

 wave base would gradually accumulate in front of the mouths of these 

 streams faster than elsewhere and a subaqueous platform would gradually 

 be built. This platform would be the initial feature for the building up 

 of a delta in later stages of the lake's history, had it happened that the 

 supply of waste brought by the streams was greater than the shore 

 processes were able successfully to distribute. This platform must also 

 have hastened the rate at which the spit, once started, could have been 

 built up, siuce it would reduce the amount of filling that otherwise the 

 shore processes would have to perform. 



Lake Ontario stood at its present level long enough prior to the forma- 

 tion of Toronto island to cut a sea-cliff along the shore that now forms 

 the mainland adjacent to the harbor. The old bench line can be traced 

 for some distance east of the Don, but opposite the eastern end of Ash- 

 bridge bay, if the old abandoned beach exists, it is not readily distin- 

 guishable. There is enough of the old beach discernible to show that 

 Lake Ontario waves were once actively cutting at the Don mouth, from 

 which it is inferred that at that time the Don delta was not encroaching 

 on the lake shore. 



Coming west from Scarboro along the lake shore, one readily notes 

 that there is a rather obtuse angle between the shoreline in front of the 

 bluffs and that of the old beach back of Ashbridge bay and Toronto 

 harbor. An examination of the present shore will show several other 

 places where similar abrupt changes in the direction of the shoreline 

 occur. One of the most salient of these points is Eaby head, near Port 

 Darlington. On a number of occasions, when strong storms were blowing 

 from the southwest, the writer has observed the waters of the longshore 

 current moving eastward along the coast and discharging out into the 

 clear waters of the lake off Eaby head. The discolored water, which 

 marked the course of the current, could readily be seen for as much as 3 

 miles east of the head, lying probably about 2 miles offshore, with clear 

 blue water between it and the mainland. At Eaby head at the present 

 time no prominent bar has been built to reach above water level and the 

 soundings available are not detailed enough to show that a bar exists. 



