THE POLAR GLACIERS. 35 



at this time, almost if not quite to the tropics, extended one vast 

 sheet of ice. It reached far into Brazil, it covered Southern 

 Africa and lapped over on Australia. The marks are all there, 

 scored on the solid rocks, to show how it crept up the southern 

 slopes of the hills, and how far it pushed its icy arms. In South 

 America at least, there is ample proof that the great glacier 

 spanned the southern ocean to reach it ; for the furrows on the 

 rock-beds of Patagonia are from the pole toward the equator, 

 whereas in any other case they would have been from the moun- 

 tains to the sea. With such a state of things at the southern end 

 of the world, with probably miles in depth of ice and sea in its 

 higher latitudes, there could have been but little water left for 

 the opposite northern regions. What is called the Atlantic-cable 

 plateau, between Newfoundland and Ireland, was very possibly 

 the north shore of the Atlantic Ocean ; and probably no consid- 

 erable bodies of water existed anywhere north of that parallel. 

 The present continents were all mountain table-lands, far from 

 the vicinity of evaporating surfaces. Like all such elevated 

 regions, not exposed to specially moist winds, they were doubtless 

 dry and arid deserts. However warm may have been the climate 

 of the north temperate and arctic zones during this their great 

 summer, their great elevation and the want of any kind of water- 

 supply must have made them barren of all forms of animal or 

 vegetable life. Consequently there would be, as is notably the 

 case, but few if any traces of this part of the great season left 

 in the geological records, at least above the present seas. 



Five thousand years pass, and the perigee has advanced to 

 meet the vernal equinox. The spring season is now the shortest 

 of all ; but as the autumnal is correspondingly lengthened, the 

 average climate is about that of the present time. But it is the 

 season of the great thaw the breaking-up time of the southern 

 hemisphere, and the waters are returning to fill the northern 

 ocean-beds. Imperceptibly a permanent white cap begins to 

 fasten itself to the heights of the boreal zone, to extend its out- 

 line, and to increase its depth. Slowly the lands are being sub 

 merged and the oceans broaden out, till there comes a. time when 

 land and water are equalized in the two hemispheres, and the 

 climates are substantially alike. 



