186 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jail. 11, 



soil above it *. Hugh Miller tells us that in making a gas-tank at 

 Rothesay, in the Isle of Bute, a bed of peat-moss, abounding in re- 

 mains of trees and hazel-nuts, was found covered by seven feet of 

 gravel. Miller classes this peat-bed with the submarine forests, 

 and the overlying gravel he considers to be a raised beach (Sketch- 

 book of Geology, p. 321). The peat here was 18 inches deep, and 

 rested upon stratified sand and clay with marine Arctic shells. 



De la Beche, in his Report on the Geology of Cornwall, Devon, 

 and West Somerset, informs us that in the South of England these 

 submarine forests are generally covered by estuarine deposits and 

 gravel beaches containing shells of the species now living on our 

 shores, and in the twenty-fourth chapter of his ' Geological Observer,' 

 he gives a most instructive account of the subject in general. It 

 seems to me that we entirely misapprehend the significance of these 

 phaenomena, if we suppose them to be due to mere local accidents 

 that have affected a small bit of ground here and there along the 

 coast. In truth they may be traced round the whole of Britain and 

 Ireland, from Orkney to Cornwall, from Mayo to the shores of Fife, 

 and even, it would seem, along a great part of the western sea-board 

 of Europe, as if they bore witness to a period of widespread elevation, 

 when Ireland and Britain with all its numerous islands formed one 

 mass of dry land, united to the Continent, and stretching out into 

 the Atlantic. Indeed, without something of this sort, how can we 

 account for the immigration . of all the land animals and plants that 

 have overspread these islands since the close of the Glacial period. 

 They have all come from Europe, and how were they to get into 

 Ireland, the Isle of Man, the Hebrides, and all the numerous islands 

 of our west coast, without a land- route being open to them ? Ice 

 might have formed a bridge to some, but not to the greater part ; 

 and I maintain that the introduction of the present land flora and 

 fauna of Scotland is almost wholly Postglacial, that is to say, pos- 

 terior to the marine glacial beds, or the period of great submergence. 



This bed of peat lying beneath the raised estuarine beds is the first 

 appearance of that substance we meet with in Scotland ; indeed the 

 period during which peat was formed so extensively from the gra- 

 dual accumulation of mosses, sedges, and various other plants, is 

 perhaps even a stage later ; for at the bottom of many of our peat- 

 mosses we find remains of trees, and in some cases beds of shell- 

 marl. These trees are aU of existing species, now indigenous to 

 Scotland. The Birch, Hazel, and Oak are amongst the most common, 

 and hazel-nuts are frequently found. Now these trees testify, I 

 think, to a condition more favourable to the growth of wood than 

 what we have at present. They evidently preceded the commence- 

 ment of the peat in a multitude of instances, for their roots are 

 spread on the hard earthy subsoil beneath it, and it is since the 

 death of these trees that many of our peat-mosses date. I am quite 

 aware, however, that many extensive swampy mosses contain no 

 remains of trees. The present or historical period is the true peat- 

 period for Scotland ; for this substance is growing rapidly just now, 

 -» Trans. Eoy. Soc. for 1799, p. 145. 



