Great Valley of the Scottish Lowlands. 117 



Mr De La Beche, in a recent work on theoretical geology, * 

 from a consideration of the facts connected with these coal-mea- 

 sures, is led to the conclusion, that, at the period when the carbo- 

 niferous limestone of the south of England was produced in the 

 sea, there was probably dry land in the part of the European 

 area not far to the northward of the present Tweed, and that a 

 gradual rise of the land was effected, by which means terrestrial 

 vegetation travelled farther to the south, so that its remains be- 

 came abundantly entombed in that direction, producing the coal 

 now found in Southern England and Wales, as also in Belgium 

 and Northern France, the continuity of the whole being super- 

 ficially concealed by the more recent secondary and tertiary de- 

 posits of those countries. 



But, as Mr De la Beche so justly and eloquently adds, f 

 " To trace even the probable positions of dry land over the Eu- 

 ropean area at the carboniferous epoch, would be most difficult, 

 particularly when we recollect that what we term a geological 

 epoch, may include a long series of ages, and that thus land may 

 rise and fall, be degraded and replaced, sometimes by the same, 

 sometimes by greater, intensities of various forces than those the 

 effects of which we daily witness, and yet the whole be included 

 in a geological epoch, or rather one during which a particular 

 group of rocks has been formed." 



* Geological Researches, p. 318. f Ibid. p. 322. 



