BRITISH POSTGLACIAL &> RECENT DEPOSITS. 405 



farther into the North Sea than is now the case. [Probably 

 this stage was synchronous with the reappearance of a vigorous 

 forest-growth in the lower reaches of our great estuaries.] 



5th, The sea again advanced and cut back into the Montrose 

 basin, upon the margin of which we now find low bluffs formed 

 of the old Scrobicularia- silt and the overlying estuarine or 

 brackish-water Carse-Clay. 



Such then is a brief outline of the successive changes which 

 took place in the valleys of the Tay, the Forth, and the South 

 Esk in Postglacial and Eecent times. That these mutations were 

 not merely local but characteristic of a much wider area is 

 proved by copious evidence. The buried land-surfaces of the 

 Tay and the South Esk have their counterparts in the so-called 

 submarine forests and peat which occur at many different 

 places all round the shores of Scotland, 1 and similar submerged 

 land-surfaces are common upon the coasts of England and 

 Ireland. The position of most of the Scottish " submarine 

 forests " is clearly at or near the base of the true postglacial 

 series. They rest upon various members of the glacial series — 

 sometimes upon boulder-clay, at other times upon the sands and 

 clays pertaining to the close of the Glacial Period. Thus they 

 demonstrate that after the disappearance of glacial conditions 

 the sea retired from all the low grounds of Scotland, and the 

 land acquired a considerably wider area than it now possesses. 

 They further show that the climate at the time of their growth 

 could not have been less genial than it is at present ; indeed, 

 as I shall endeavour to prove, the climate must actually have 



1 For descriptions of Scottish submarine forests and peat, see Edinburgh 

 Philosophical Journal, vol. iii. p. 100 ; vol. vii. p. 125 ; Sinclair's Statistical Ac- 

 count of Scotland, vols. vii. p. 451 ; x. p. 373 ; xiii. p. 321 ; xvi. p. 556 ; New 

 Statistical Account of Scotland, vol. i. pp. 16, 243 ; Trans. Royal Soc. Edin., vols, 

 ix. p. 419 ; xxiv. p. 363 ; Quarterly Journal of Science, Literature, and Art, vol. 

 xxix. p. 21 ; Mem. Wemerian Soc, vol. v. pp. 24, 440 ; Trans. Highland Soc, 

 vol. vii. (1841) p. 17; Quart. Journ. Gcol. Soc, 1865, p. 183; 1867, p. 196; 

 Anderson's Practical Treatise on Peat- Moss, p. 150 ; Bany's Orkney Islands, p. 

 282 ; Miller's Sketch-book of Geology, p. 321 ; and Edinburgh and its Neighbour- 

 hood, p. 91 ; Journal of Botany, vol. v. (1867), p. 174 ; Trans. Bot. Soc. Edin., 

 vol. ix. (1868), p. 146 ; The Great Ice Age, 2d ed., p. 307. 



