BRITISH POSTGLACIAL d- RECENT DEPOSITS. 423 



many of them attained a great size. They were found lying in 

 all directions beside their roots, and were buried under peat to 

 a depth of fourteen feet in places. The average thickness of the 

 peat, however, was about seven feet. Here, then, we have clear 

 evidence to show that after the retreat of the sea from the wide 

 Carse -lands of Stirling, a strong forest -vegetation eventually 

 occupied the vacant ground. During the formation of the 

 Carse-clays, the climate, as I have endeavoured to show, must 

 have been cold and ungenial ; the Highlands and Southern 

 Uplands had then their permanent snow-fields ; local glaciers 

 occupied many of the mountain-valleys ; and streams and 

 rivers were frequently torrential in character. While these 

 conditions prevailed it seems most likely that the forests must 

 have disappeared from a large part of the country. The 

 reappearance of great forest-trees, however, rooted in the Carse- 

 clays, shows that the climate afterwards became genial as 

 before. Nor are there wanting indications that seem to show 

 that the land during this second forest-growth extended farther 

 out to sea. At Montrose, as we have seen, the brackish-water 

 Carse-clays, upon the surface of which peat with trees occurs, 

 have evidently at one time stretched farther seawards. They 

 now form low bluffs along the present sea-margin. 



The occurrence of at least two successive tiers of trees in 

 certain of the inland peat -mosses seems to me to point to 

 similar climatic changes, and I feel inclined to attribute more 

 importance to the fact of such a succession, than to the preva- 

 lence in a given bog of any one particular kind of tree. Were 

 the Scottish peat-mosses as well opened up as those of Norway, 

 I should expect to find the appearance of two or more tiers of 

 trees a common feature in most of our extensive bogs, for it is 

 so in the case of Irish and English peat-mosses. So far as the 

 evidence goes, it leads me to look upon the successive buried 

 forests of some of the inland districts of Scotland as probably 

 synchronous with those old forest-beds which make their appear- 

 ance below and above the Carse-clays — that is to say, that the 

 submarine forest of the Tay, etc., is contemporaneous with the 



