No. 5.] SPENCER — SURFACE GEOLOGY. 303 



gravel, we see simply a high rid^e of laud with beach markings 

 all the way down from the summit (over 1700 feet ab(jve the seai 

 to an altitude of about 950 feet, surrounded by one succession of 

 old water-margins, indicating the gradual growth by elevation of 

 a rocky or generally rocky island, for the ''Artemesia gravel" 

 reposes (as far as I have been able to learn) on hard rocks or 

 stratified clays, except in the old buried channels of tributaries of 

 the ancient Grand river (principally). Surrounding the old 

 island we find in several places rude terraces of about the same 

 altitude, at many miles apart. Yet the waters did not linger as 

 lon2,' to form marked terraces as at lower levels. This general 

 ■deposit in no way partakes of the character of a Scotch kame. 

 even though we considered the ''Oak ridiie " of that character, 

 as the latter much more nearly resembles one in outline, relative 

 direction and composition than tlie Artemesia highlands. The 

 whole series of beaches aud terraces about Lake Ontario marks 

 the slow elevation of the continent, causing' lands at various ele- 

 vations to be covered somewhat uniformly witli the gravel and 

 sand, and again somewhat intermittently, producing well marked 

 terraces. Nor did this subsidence of the waters cease when the 

 present lake level was obtained, as we have a comparatively 

 modern ledge, carved out of the soft Medina rocks near the outlet 

 of the Welland canal, belov; the surfcice of the lake and extend- 

 ing downwards for a known depth of more than forty feet. This 

 fact would indicate local oscillation of the margin of the present 

 lake basin. 



I fail to compreliend how any glacial lake could have existed 

 when it was producing terraces over all the great lake region at 

 an elevation of what is now 1700 feet above the sea, for the sur- 

 face of the waters was not covered with any great amount of ice 

 — perhaps not much more than the ice-fringes of the present day. 

 •Many portions of the southern highlands do not rise to any such 

 altitude to be easily barricaded with the small amount of floating 

 ice indicated by the transported material. 



There seems a difficulty in explaining the absence of marine life 

 in this area when it is found in the bed of the St. Lawrence val- 

 ley, unless the whole pei-iod was one of comparatively short du- 

 ration, aud marine life did not get farther westward than the 

 present outlet of Lake Ontario. 



The Draiuayt of tlu Inland Sea. — This inland body of water. 

 as the coutiueut was i;raduallv rising- from beneath the sea level. 



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