Lammermuir Hills. 301 



exaggerate the amount of denudation that these ancient 

 rocks have suffered in the Highlands. 1 Fig. 56, p. 289. 



Farther south the different nature, both of the Silu- 

 rian and newer rocks, coupled with other geological ac- 

 cidents, have produced the great valleys of the Forth 

 and Clyde, and the tamer but still hilly scenery of the 

 Southern Highlands, as they are sometimes called 

 These consist mainly of the Lammermuir, Moorfoot, 

 and Carrick Hills, now often massed under the name of 

 the Lammermuir range. But they are not a range. 

 They consist in reality chiefly of a tableland, or old 

 pldin of denudation, older for the most part than the 

 Old Red Sandstone and Carboniferous rocks ; which 

 plain, after being long buried, was subsequently again 

 exposed by denudation of the overlying strata. 



The present scenery of hill and valley in the 

 southern part of Scotland is therefore, in great part, the 

 result of the waste of this old tableland, and the scoop- 

 ing out of valleys and lake-basins, by rain, rivers, and 

 old ice, which, as a great ice-sheet, at one time covered 

 the whole of Scotland and much more besides. The 

 effects of this were, in later times, modified by minor 

 glaciers, during those oscillations of temperature that 

 marked what we now call the Glacial epoch, and all the 

 ordinary water produced by rain and rivers is modifying 

 the scenery now. 



1 For cases in point see my memoirs on The Geology of North 

 Wales,' and ' On the Denudation of South Wales and the Adjacent 

 Counties,' < Memoirs of the Geological Survey,' vol. i., 1846. 



