132 W. A. E. Ussher—" Prehistonc Europe"— 



rally sustained." After illustrating his objection by a reference to 

 the Happy Union Section described by Mr. Colenso at Pentuan, he 

 arrives at the conclusion that the ancient forest-bed on the streain- 

 tin-gravels is a relic of an older land surface than that represented 

 by the submarine forests on the present coast-line. 



Had I stated that the forest-beds in question were generally cor- 

 relative vi^ith the traces of vegetation from time to time discoverable 

 on the present foresliore, I should have committed the egregious 

 error into which Prof. Geikie thinks I have fallen, and that upon 

 the single favourable datum furnished by Mr. Game's section of 

 Huel Darlington mine in the vicinity of Mounts Bay. 



In Post-Tertiary Geology of Cornwall (printed for private 

 circulation in 1879), p. 45, I have stated my views as follows : " The 

 growth of the old forest, the relics of which have been met with all 

 round the Cornish coast, must have extended over a long period of 

 time. The evident connexion of the Mounts Bay Forest with the 

 bed in Marazion Marsh overlying stream-tin, pointed out by Mr. 

 Came ; and the constant presence of a distinct vegetable stratum, or 

 of detritus mixed with vegetable matter, on the tin-gravels in most 

 of the principal sections, points to a general correlation of the sub- 

 merged forests on the coasts with the forest-bed in stream-tin 

 sections." I did not anticipate the acceptation of the phrase 

 " submerged forests on the coasts," in the above passage, in so 

 littorally literal a sense as "the submerged forests exposed upon the 

 present foreshore," as Prof. Geikie has rendered it, but meant by it 

 the extensive tract of which these traces between high- and low- 

 water mark are the only observable relics — a tract of the extension 

 of which I have taken (op. cit. p. 43) the depths of the stream-tin 

 gravels of Par, Pentuan, Carnon, etc., below the sea-level to be 

 indicative. 



I conceive the forests to have flourished over a wide area extend- 

 ing beyond the limits of the present coasts. That this area was of 

 the nature of a great plain broken and stepped by old marine terraces 

 modified by subaerial denudation, and that it was breached by 

 valleys representing the then existing lines of drainage and also 

 clothed with vegetation. As a gradual subsidence narrowed the 

 limits of the forest tract, the sea in its advance would naturally 

 encroach upon the valleys, and if the forest growth continued un- 

 impaired on the plain, and in its inequalities, the lower tracts would of 

 course be first submerged, and their submersion could not be regarded 

 as strictly synchronous with that of the forest belt fringing parts of 

 the foreshore where no such depression existed. 



But here again I must guard myself against misunderstanding. I 

 do not think that those parts of the forest which had taken root in 

 the tin ground in the valleys were left in undisputed possession of 

 those positions from their first growth \intil the access of the sea to 

 their sites (Vide Pleistocene Geology of Cornwall, Part IV. General 

 Notes on Submerged Forests and Tin Gravels, Geol. Mag. for 1879. 

 " To synchronize the forest remains in the various sections, etc.," 

 and "In like manner the duration of the forest growth, etc.") 



