BRITISH POSTGLACIAL & RECENT DEPOSITS. 415 



glaciers occupied the longest Highland valleys throughout their 

 entire extent, yet this does not help us to explain the great con- 

 trast in point of preservation which obtains between the two 

 series. The latest moraines are evidently of much more recent 

 origin than the more or less degraded moraines which are met 

 with in the lower reaches of the same valleys. 



Are we to believe, then, that the glaciers of the old Ice Age 

 continued to hold their own from the close of that period down 

 to the time when the Carse-clays were deposited ? This in itself 

 is highly improbable, as I shall point out afterwards, when we 

 come to sum up all the evidence bearing upon the question of 

 postglacial climate, but for the present the improbability of 

 the hypothesis is rendered sufficiently obvious by the small size 

 of the moraines in question. If local glaciers occupied the 

 upper reaches of the longer valleys of the Highlands and 

 Southern Uplands from the close of the Glacial Period down 

 through that of the " buried trees " and " submarine peat," and 

 on to the time when Carse-clays were deposited and Neolithic 

 man occupied Scotland, we might surely have looked for very 

 much larger moraines in place of the small cones and ridges 

 which actually occur. The more reasonable explanation of the 

 phenomena appears to be that which infers that after the final 

 dissolution of the glaciers at the close of the Glacial Period, 

 perennial snow and ice either disappeared entirely for a time or 

 were reduced to very insignificant patches, and that, at a sub- 

 sequent period, they again increased, and local glaciers, some- 

 times attaining a considerable size, once more occupied the 

 mountain-valleys, and deposited a newer series of moraines. Nor 

 is this explanation based simply upon the fresher appearance 

 and generally smaller size of these moraines, as compared with 

 the often much- worn and older aspect of the more widely-spread 

 erratic detritus at lower reaches in the same valleys. Now and 

 again one may notice how the latest local glaciers have partially 

 overridden the heaps of dibris which had gathered in the valleys 

 after the disappearance of the glaciers of the last cold stage of 

 the true Glacial Period, while in other cases they have even 



