BRITISH POSTGLACIAL &> RECENT DEPOSITS. 407 



CHAPTEE XVII. 



POSTGLACIAL AND KECENT DEPOSITS OF THE BEITISH 



islands — Continued, 



Larger size of Scottish rivers in Postglacial times — Local glaciers then reached 

 the sea-level — Recent glaciation in mountain-valleys of Scotland — Contrasts 

 between glacial phenomena of the Ice Age and Postglacial times — Examples 

 of postglacial moraines — Interval between the close of the Glacial Period 

 and the reappearance of local glaciers in Postglacial Period — Scottish raised- 

 beaches — Peat-bogs of inland districts — Buried forests in peat-bogs — Correla- 

 tion of these with the submarine forests and peat of the maritime districts — 

 Age of the Scottish peat-bogs — Alluvial deposits of Scotland — Their organic 

 remains— Correlation of archaeological epochs with geological stages in Post- 

 glacial history of Scotland. 



The rivers of Scotland, as I have said, flowed during a certain 

 stage of the Postglacial Period in deeper volume than at present, 

 a conclusion which is based partly upon the coarse and tumultu- 

 ous character of their gravels, and partly upon the fact that 

 their flood-loams cover much wider areas and reach to much 

 higher levels than any similar deposits pertaining to the rivers 

 of more recent times. If one wished to compare the work done 

 by the rivers of our own day with that which the same streams 

 were capable of accomplishing in postglacial times, he would 

 do well to trace some such river as the Tweed, the Tay, or the 

 Clyde, from its source to its mouth. He would note that, even 

 in the upper reaches of the river and its tributaries, the valley- 

 bottoms often show old water-levels at heights to which the 

 streams cannot now attain. These old levels are composed for the 

 most part of coarse gravel and shingle, with now and again 



