PALEOLITHIC RACES 329 



the abrasive action of the glacier, which has ground away all 

 the asperities of its bed ; crags and jutting rocks have been 

 worn down into rounded bosses (roches moutonnees), the smooth 

 surfaces of which are striated by grooves and scratches all running 

 in the direction of the stream-lines of the once-flowing ice. 



The drumlins would be found to consist of a tough clay 

 crowded with stones of all sorts and sizes, but bearing very 

 remarkable features by which they are readily distinguished. 

 Originally angular fragments, they are now subangular, their 

 sharp edges and corners having been ground away and rounded 

 off by the ice ; their flattened faces are smoothed and polished, 

 and covered with scratches which run in parallel groups, 

 generally in the direction of the longest axis of the stone, but 

 occasionally crossing this direction. The whole assemblage of 

 scratched stones and clay is known as till or boulder clay. 



Such, then, are the signs which would be left behind on the 

 disappearance of the ice. 



It requires no magic wand to bring about the transformation 

 we have imagined ; an amelioration of climate will suffice. Even 

 at the present time the Boden glacier, like so many other great 

 glaciers in Switzerland, is diminishing in bulk ; its surface, instead 

 of bulging up, is sagging in like an empty paunch, since the 

 annual snowfall is insufficient to make good the annual loss due 

 to melting away. A general rise of temperature over Switzerland 

 to the extent of 4 or 5 C. would probably drive the snow-line 

 above the mountain peaks, and all the glaciers would disappear. 



Let us now suppose that the climate, instead of ameliorating, 

 grows gradually more severe. The Boden glacier will be more 

 richly replenished by its tributaries ; it will bulge upwards and 

 downwards, and descend farther into the valley of the Visp ; if 

 the mean annual temperature falls low enough — say, 5 C. below 

 the present — it will extend downwards till it reaches the valley 

 of the Rhone. All the glaciers which lie in valleys tributary 

 to the Rhone will similarly enlarge, as will the glacier of the 

 Rhone itself. 



If, bearing this possibility in mind, we walk down the valley 

 of the Visp, we shall discover on every side evidence of an 

 ancient extension of the ice, and on the most stupendous scale. 

 The swollen Visp glacier soon became confluent with that which 

 filled the Sass-thal, and their united volume then entered the 

 glacier of the Rhone. This, which now ends close to the Furca, 



