BRITISH POSTGLACIAL 6- RECENT DEPOSITS 419 



So long as our observations are confined to the Postglacial 

 and Eecent marine deposits, and the terrestrial and freshwater 

 accumulations which are now and again intercalated with these, 

 we experience generally little difficulty in assigning to each bed, 

 or series of beds, its proper place in the succession. But when 

 we seek to discover the relative age of those lacustrine and peat 

 formations which are scattered over the inland districts, we have 

 little to guide us in coming to any definite conclusion. As a 

 rule, all we can assert is, that they are for the most part of post- 

 glacial and recent age. It is quite impossible, however, to refer 

 each particular deposit to its proper place in the series. Yet 

 there can be no doubt that the submarine trees and peat must 

 have their representatives in the interior of the country, although 

 we may be seldom able to pronounce upon these with confidence. 

 This arises from the circumstance that trees representing ancient 

 forests are found buried under peat in positions which clearly 

 prove them to be of later date than the Carse-clays and beach- 

 deposits of the lower level (25-30 feet above the sea), and no 

 inconsiderable portion of the peat with enclosed trees, which 

 occurs in the inland districts, may belong to this later period. 

 The age of forest-growth represented by the submarine trees of 

 the Tay, the Earn, the Forth, and other maritime districts, was 

 followed, as we have seen, by a period of greater humidity, accom- 

 panied by a lower temperature. These changed conditions must 

 have told upon the flora throughout the length and breadth of 

 the land. Arboreal vegetation in the neighbourhood of the sea 

 would languish and disappear, and the upward range of oaks 

 and other trees upon the hill-slopes of the interior would become 

 more limited. The increased humidity would, at the same time, 

 give a great impetus to the spread of mosses and marsh-plants, 

 and wide regions formerly covered by trees would eventually 

 become wrapped in a mantle of peat. Hence, we may well 

 believe that many tracts of buried trees and thick peat may 



(1839), p. 228; Fleming's Lithology of Edinburgh, p. 85; Hugh Miller's Sketch- 

 book of Geology, pp. 14, 60 ; A. Geikie's Scenery and Geology of Scotland, pp. 193> 

 318. 



