ClIArTEli IV. 



PHYSICAL AND C;LTMATAL C;ONr)ITIONS 



(CoNTINTKU). 



//. — CatiHCfi of GUu'ldfitiii <(H<I DiHlrilnifiiiu of ErvitticH — Coiiiiiincd. 



2. -SEA-BORNE ICE. 



2. Wo now come to llic ([ucslloii of dispersion of 

 Louldeis iiiid tovuiation of lioiddcr-cliiy and striated 

 surfaces by lloaliu^' ice, wlietlier formed on the sea or 

 derived from the ends of glaciers discliarging at the level 

 of the sea. Here we may take for granted the great 

 submergence of the North American continent, first in 

 the early glacial period, and sul)se(jnently to a still 

 greater extent in tiie later glacial period, and that this 

 submergence was in the earlier })eriod dill'erential, affecting 

 the plains and not the mountains. 



I shall first quote here a letter received several years 

 ago from my friend, Dr. John llae, F.K.8., a traveller of 

 almost nnrivalled arctic experience,* and which shows 



* September, 1882, Tlie same facts are referred to in a paper l)y 

 Dr. Rae in the Journal of the Physical Society, 1881. 



