CHAP, in.] THE BRITISH MEIOCENE FORESTS. 47 



as rich as that of the continent, leaving behind a few 

 fragments preserved from destruction by the great origi- 

 nal thickness of the deposit, or by its having been covered 

 up by showers of ashes and streams of lava from the 

 Meiocene volcanoes. 



The Meiocene Rivers. 



The rivers of Britain in the Meiocene age (Fig. 6) 

 were probably in the position which they now occupy, 

 although they flowed at a higher level the only differ- 

 ence being that their lower courses were prolonged 

 to the coast-line of the period. The Severn, for ex- 

 ample, and the Dee, Mersey, and Eibble, would debouche 

 into the Atlantic after traversing the lower grounds 

 now submerged. The Trent and Humber, in like 

 manner, would find their way into the south-eastern 

 sea. 1 Some of the Irish lakes also such as Lough 

 Neagh were lakes then. In Devonshire the small lake 

 of Bovey reflected on its still surface the luxuriant 

 forests by which it was surrounded. 



The British Meiocene Forests. 



The Meiocene forests of Britain, preserved in the 

 deposits of ancient lakes, or buried under volcanic ashes 

 and lavas, occur merely in a few isolated spots in Devon- 

 shire, the Scotch isles, and in Ireland. 



The lignites of Bovey Tracey, 2 to the south-east of 



1 Ramsay (Physical Geology and Geography of Great Britain, p. 217, et 

 seq.) believes that the lower part of the valley of the Severn and the" whole 

 of the Thames valley are post-Meiocene. 



2 The Lignites of Bovey Tracey, by William Pengelly, F.R.S., and Dr. 

 Heer. Phil. Trans. 1862. 4to, 1863, p. 18. 



