422 PREHISTORIC EUROPE. 



there can be little doubt that similar observations carried on in 

 Scotland would greatly increase our knowledge of the climatic 

 changes which supervened upon the introduction of the Ger- 

 manic flora. 



Be that, however, as it may, the evidence that we have is 

 yet sufficient to prove, 1st, that Scotland was formerly more 

 extensive, since many peat-bogs in the maritime districts, both 

 of the mainland and the adjoining islands of the Inner and 

 Outer Hebrides, and the Orkneys and Shetlands, contain 

 abundant remains of large trees which could not possibly have 

 grown under present conditions ; 2d, that the climate which 

 induced oaks to grow on the exposed hill-slopes in the north of 

 Scotland at an altitude of 3000 feet, must have been more 

 genial than the present; 3d, that the large pines with their 

 thick bark and resinous wood which occur in certain lowland 

 mosses, seem to point, on the other hand, to a somewhat colder 

 climate. The evidence of the pine would thus appear to clash 

 with that of the oak. But I think this is partly due to the fact 

 that the buried forests really pertain to at least two horizons, 

 and that in many cases the trees obtained from different levels, 

 in one and the same bog, may have been confounded. Nothing 

 indeed, is more likely than that the fact of two successive 

 growths of forest-trees may have passed unnoticed, for some- 

 times the trees of an upper forest-bed have grown immediately 

 upon the prostrate trunks of a lower series, with only a foot of 

 peat separating the one forest-bed from the other. 



I have already described the buried forests of the Tay, the 

 Earn, and the South Esk, and the drifted trees in the Carse-cla) T s 

 of the Forth, and have shown that these grew at a period 

 anterior to the formation of the great estuarine flats. Now 

 upon the surface of those flats an upper forest-bed occurs 

 covered over with peat which reaches a depth in some places of 

 more than a dozen feet. Under the moss of Kincardine 

 (estuary of the Forth) were found innumerable trees and stumps 

 rooted in the subjacent Carse-clay. The trees consisted of oak, 

 birch, alder, willow, mountain-ash, hawthorn, and hazel, and 



