THE MAKING OF MOUNTAINS 43 



aspect of the Highland area when the mountains began 

 to be shaped out by Nature's saws and chisels." It 

 should be noted that the great Highland Plateau, 

 which has been so wonderfully carved, is in some 

 places a plateau of accumulation as well as of erosion. 



What is true of the Scottish Highlands is true also 

 of the Southern Uplands. Great Folded mountains, 

 buckled up in very ancient (Palaeozoic) times, have 

 been worn down and in some cases base-levelled. Much 

 of the plain of erosion was then submerged and loaded 

 with sedimentary rocks, such as shales. It was then 

 bulged up into a plateau, which, like that of the High- 

 lands, was partly a plateau of accumulation and partly 

 a plateau of erosion. Then followed the long carving 

 out of the tableland into broad-topped and flat-topped 

 hills, much tamer than the Highlands except in Gal- 

 loway. It has to be remembered that the prevalent 

 rounding of Relict mountains, in contrast to the preva- 

 lent peaking of Folded mountains, has been made 

 more marked by severe glaciation, in Southern Up- 

 lands and in the Highlands alike. 



The mountains of the Lake District, of Wales, of 

 Ireland, of Norway and Sweden, and the elevated 

 tracts to the north of the Pyrenees, Alps, and Car- 

 pathians are all monuments of erosion; indeed, these 

 Relict mountains occur in most parts of the globe. 



Two final cautions we venture to make. The first is 

 that plateaus of accumulation may mingle with 

 plateaus of erosion, and, what is more important, that 

 it is not always easy to draw the line between the 

 Original mountain range and the carved-out plateau. 

 For a considerable residue of Folded mountain or Vol- 

 canic mountain may remain in the tableland that is 



