.1. w. SPENCER — A.NCIENT SHORE PHENOMENA. 



action below the Burface of the water, for at greater depths the fine earth 

 would not have been removed from beneath the stones. The vertical range 

 ofthe fringes is from fifteen t>> twenty-five feel or more when the recession 



• 



Hi' the former waters was gradual, leaving a close succession of beaches. The 

 width ofthe pavements varies from a few hundred feel to perhaps a half a 

 mile, according as the Blope is somewhat steep or very gradual. When the 

 finer materials were entirely washed oul into deeper water, then the mar-ins 



• be plains, at the fool ofthe old coast-line, are simply fringed with boulders ; 

 but when the liner materials were assorted by the waves ami currents, the 

 Bands and gravels have been formed into beaches, usually a few feet above 

 the level of and behind the boulder belt. 



But the storj ofthe boulder pavements and fringes is nol yet complete. 

 I ist-ice lias also played an important part in the arrangement of the pav- 

 ing Btones. The wave-, acting upon the coast-ice wherein boulders have 

 been entangled, cause the st-m- to he forced up into more regular /.ones, 



■ . height, than would be affected by the residuary deposition alone, as 

 1 1 1 — t described. Blocks of large size can thus be moved, not merely by the 

 heaving action of modern frosts, but by the action of coast-ice itself; for 

 boulders upon the margins ofthe St. Lawrence river, weighing seventy tons, 

 are known to have been shifted by the spring vements of a winter's ice. 



ain, the writer has seen upon some of the shores of Shoal lake, in 

 Manitoba, situated in a flat drift-covered country, modern beaches composed 

 of huge boulders, piled up by the waves of the lake acting upon the ice in 

 which the -tone- were enclosed, as otherwise blocks four or six feel long 

 could not be gathered from the shores of the lake and accumulated into 

 beach ridges, nor could they have been residual pavements as above 

 described, for no high shore- of boulder clay occur into which the waves 



,ld have made encroachments. 



An excellent illustration of the modern formation of boulder pavements 

 and fringes may be seen upon the shore- of Georgian hay, between Thorn- 

 bury and < k>llingwood, as -how o in Plate 1 , fig. '_'. There Lhe lake wave- are 

 encroaching upon a shore composed of boulder clay. The larger stones 



nt in the water arc too heavy to be materially affected by the 



waves or ice action. Excellent illustrations of boulder zones are found a 

 -hoit distance from this locality, at an elevation of 1*7 feet above the lake, 



how n in Plate I . fig, 



< nhcr i samples of fi f boulders high above any modern waters may 



miles beyond the eastern end of Like Ontario. 'The same is 



true u | the northern Bide of the lake, as for example, back of Trenton and 



•ward : these are parts of and in front of the finer gravels of an old beach, 



i han four hundred feet above the lake. Westward of Toronto, 



where the old Paleozoic in place of drift, the boulder 



from thi front of the beach. 



