GYMNOSPERM^. 



79 



no other trace remains. The Faroes are even more eloquent of waste. This little 

 group of some twenty islands and islets presents the ruins of a once continuous plateau, 

 2000 or more feet in height. The hills, as in Iceland, are usually flat-topped, but 

 the cliffs, frequently 1000 and sometimes 2000 feet high, are almost vertical, and are 

 fretted, especially on their western faces, into weird and fantastic forms. The sub-aerial 

 waste is here supplemented by the attacks of the waves, and the sea for miles round is 

 shallowed by the redeposited silt. 



*' Some of the noblest hills of the Inner Hebrides are but solitary outliers left 

 standing amid the ruin of the great sheets of solid rock of which they once formed a 

 part. Ben More, in Mull, though more than 3000 feet high, is only a magnificent 

 fragment of the huge pile of volcanic material which formerly swept over what are now 

 the deep glens and fjords of Mull. The long lines of imposing cliff with which the 

 basalt plateaux front the Atlantic all through these islands, from the Fair Head of 

 Antrim to the far headlands of Skye, tell everywhere the same tale of vast and con- 

 tinuous denudation." ^ " But most strikingly of all is this fact of enormous denudation 

 of the Scottish Highlands during very recent geological periods, demonstrated by the 

 occurrence of post-Miocene faults, having downthrows of various amounts up to nearly 

 2000 feet, the effect of which upon the surface has been entirely masked by post- 

 Miocene denudation." ^ When we reflect that even this colossal denudation may be 

 insignificant to that effected over tracts which are now sea, or to that which has acted 

 over land-surfaces which no longer present any shreds of Basalts, except the dykes 

 through which they welled, we feel compelled to stretch back our conception of the time 

 during which the causes may have operated to the uttermost possible limits. 



These limits cannot go beyond the White Chalk, for the lavas rest upon its denuded 

 surface or upon the capping of angular flints and loam, which denote its former exposure 

 to atmospheric influence. In Scotland, moreover, according to Judd, the Upper Chalk 

 is covered by intervening estuarine and coal-bearing strata, sufficing to negative the idea 

 that the Basalts were in any way contemporaneous with the Cretaceous series as 

 developed in Great Britain. There is no physical evidence, however, against their 

 belonging to any part of that vast period which intervened between the British White 

 Chalk and the British Eocenes, nor to any stage of the Eocenes ; but they do present 

 evidence of such great antiquity that we ought to hesitate to assign them to any later 

 period unless very good reasons for doing so were apparent. 



The plant evidence upon which they were classed as Miocene has always been of 

 the weakest description ; and, had any of the geologists who have written about them 

 troubled to look into it independently, the conclusion as to their age would never have 

 been accepted. It was somehow assumed that the Antrim plants were on the same 

 horizon as the Mull plants, and that since the latter were said to be Miocene the former 



^ Geikie, ' Quart. Journ. Geol. Soc.,' vol. xxvii, p. 285. 

 Judd, ibid., vol. xxxiv, p. 669. 



