72 THE ICK A(iK 1\ CAN'ADA. 



.sivelv shown liv scvcial ijvnld^isls * that in lliis iicri'.d 

 the valk'vs of the ureal Anu'rican lakes woiv I'XCiiviitod, 

 and llial the ancient St. l-awreiiee llnweil without any 

 lakes to tlie sea. The presiMit e'veal lakes are ]»artly 

 (lanuned u]) hy y'laeial deposils, and partly |)ro(lueeil hy 

 \vari)in!4 or dirterential ele\ation. It may now he con- 

 sidered as fully estahlished that tlie ^I'eat American lakes 

 are not the result of glacial action, hut that they are old 

 river valleys excavated in periods of continental elexation, 

 and now dammed uj) hy accumulations of ilihris and hy 

 (lill'erential elevation occurrinu' in the Pleistocene pei'iod. 

 In the great depression of that ]ieriod, they s})read 

 far more wiilely than at }»resent, as indicated hy the 

 old terraces aronnd them, some of which, acc((rding to 

 Spencer, are 1,700 feet ahove the ])resent water level, and 

 may indicate a ])eriod when the whole American land was 

 much l(.)wer than at present. (See Spencer, Journal 

 (ieol. Society, Vol. XLVl., 1890.) Further, Dr. (1. M. 

 Dawson •(• has shown that in this and prexious ]»eriods of 

 continental elevation the great fiords and canons of 

 liritisli Cohnnhia were cut out, and (piite recently 

 I'ettersen has al)ly a})})lie(l the same ex])lanation to the 

 fiords of Norway. The latter says : " 1 have, therefore, 

 after the most careful researches here, yard hy yard, and 

 extending over many years, come to the conclusion that 

 the Bahfjord is not of (jlacial oriyin, hut forracd an incision 

 or depression in the mountains of older oriejin than the 

 glacial age. And this conclusion, I helieve, ma//, in the 

 main, apply to the question of the formed ion of all fjords in 



* Newberry, Hunt, Spencer. 



t 'Superficial tleology of British Columbia, 1878. Later Physio- 

 graphical Geology of the Rocky Mountains of Canada, Trans. R.S.C., 

 1890. 



