GEOGRA PHIC FEA TURES OF SO UTHERN FA TA G ONIA 47 



recent date. In some few instances the lavas of the great interior 

 region extend westward quite to the base of the Andes, but as a rule 

 the surface of the plain for a distance of some 30 to 40 miles eastward 

 from the base of the mountains is free from lava. It has either never 

 existed there or has been entirely swept away or covered over by 

 glacial detritus, as has been observed in some few instances. 



That region lying between the western border of the lava beds and 

 the foothills of the Andes is b}^ far the most fertile of the Patagonian 

 plains. Its surface, covered to a considerable depth with glacial de- 

 posits, presents a series of ranges of low, rounded hills, left as terminal 

 moraines by the receding glaciers. Such ranges of hills have a trend 

 parallel with the base of the mountains, and are usually separated by 

 broad stretches of meadow land, with numerous small glacial lakes, 

 either occupying slight depressions in the meadows or, as more fre- 

 quently seen, embraced by the low, rounded hillocks of the terminal 

 moraines. These conditions are especially characteristic in this region 

 over the bottoms and slopes of the great transverse valle3^s, but they 

 extend also in many places out over the surface of the higher pampas- 



The rolling surface of this western plains region, abounding in wide 

 pasture lands dotted over with sparkling lakes of pure, sweet water, 

 presents a pleasing contrast to the semi-arid region near the coast, 

 and afibrds a welcome relief to the traveler after a journey across the 

 black, absolutely ban-en lava beds of the central plains. Its modest, 

 unobtrusive beauty but emphasizes the grander scenery beyond, in- 

 dications of which already appear in the distant ranges of the Andes, 

 whose summits, buried deep in fields of snow and ice, are seen bril- 

 liantly white against the intensely black background formed by tlie 

 storm-clouds of the western sky. 



Entering the confines of the Andes, numerous rivers, deep rocky 

 canons, broad open lakes of beautiful clear water, fed by glaciers that 

 descend from the snow-fields at the summits, and all the other fea- 

 tures characteristic of an intensely rugged, mountainous region, thrust 

 themselves upon the attention and excite the wonder and admiration 

 of the traveler. 



The country l3'ing along and within the foothills of the Andes 

 is in many respects the most interesting region in Patagonia, whether 

 considered geographically or geologically. Taking advantage of any 

 of the numerous valleys that extend westward from the western 

 border of the Patagonian {)lains and penetrate not only the secondary 

 but also the main I'ange of the -Andes, finally emptying into the 



