INVOLUTION OF IRONDEOUOIT VALLEY. 145 



work keeps the silt fresh-cliffed at many points (sec explanation of 

 fief are ^) , while small deltas form at the mouths of the brooks, espe- 

 cially Densmore's and at ("ilen Haven. Since its re-entry into the 

 Bay, Ontario has not been idle. On its main shoreline also it has 

 done a notable work, though some of this may have been roughed 

 out for it by its predecessor "Vermont" as already suggested. The 

 smooth curvature of that bit of its shore that appears upon our map. 

 and the great bar completed across the mouth of the Bay, are indices 

 of maturity in this particular arc, which, it should be noted, spans 

 the space between two rock exposures, at Windsor Beach and just 

 west of Forest Lawn. 



The height of the silt blutts west of "Lake Beach" denotes that 

 Ontario has here transgressed shoreward at least a mile into the 

 delta plains of Iroquois and Emmons. To-day its waves are op- 

 posed at many points by the more resistant till, and progress is 

 slower, though sufficiently vigorous to arouse at times the appre- 

 hension of property owners and to have compelled the railway to 

 dump huge masses of rock along the frontage of its tracks. 



Besides the contributions of its own wave work, this recess of 

 the lake receives also the detritus of the present Genesee. The lake 

 currents here set easterly ; a yellow streak in the blue waters trails 

 away eastw^ard for several miles from the mouth of the Genesee 

 river. Though this is now kept a mile or more offshore by the long 

 breakwaters confining the outflow at Charlotte, its burden is still 

 borne inward toward the beach by the waves, and in the past it 

 must have added no small increment to the material that has been 

 piled into the mouth of the Bay. The soundings testify that the 

 Ontario-Genesee delta extends widely eastward and completelv 

 masks any northern continuation of the Irondequoit valley beneath 

 the water of Lake Ontario. 



One other item remains. This is the long concave silt-bluft' on 

 the east shore of the Bay at its north end, facing out toward the 

 lake and paralleled by the barrier beach. The .shaping of this is 

 plainly the work of waves from the open lake, but the bulk of 

 this cutting must have preceded the construction of the barrier. 

 Some of the shoaling of this north end of the Bav is evidentlv due 



