122 THE SOUTH COAST. 



South-East Britain. Finally, in the south- west the Tertiary strata 

 extend chiefly in an east-and-west direction, which the Wealden and 

 Cretaceous rocks also share. The Wealden elevation, which, it will be 

 noticed, extends across into France, is clearly of the same date as the 

 folds termed the London and Hampshire basins. The clue to the period 

 when those synclinal folds were formed is furnished by the newer 

 strata in the Hampshire basin. These are chiefly lacustrine and estua- 

 rine deposits, showing that the land towards the middle of the Tertiary 

 period was becoming more and more upheaved. Hence, since we 

 know that upheaval only takes place as a consequence of the lateral 

 compression of the rocks that is to say, of the formation of folds in 

 them we are led to fix the middle Tertiary or Miocene period, during 

 which much of Europe was in a state of dry land and the Alps were 

 rising, as the age when the north-to-south compressions operated in the 

 south-east of England. It will be observed upon the map that the east- 

 to-west extension of these newer deposits is paralleled by the similar ex- 

 tension from west to east of the Primary deposits of the south of Ireland 

 and west of England. Hence, the direction of the eastern folds seems 

 to be attributable to the persistence of an underlying resisting mass of 

 consolidated rock similar to that which determines the folds on the 

 western side of the island. It is within the limits of possibility that 

 the Dogger Bank and the Yorkshire moorlands may show, by their 

 eastern extension, limits of this Miocene compression on the north. 

 Thus the several portions of Great Britain have been formed gradually, 

 and although we have only considered the main folds which influence 

 the directions in which a coast extends, still the effect of these com- 

 pressions is obvious in the great east-to-west extension of the southern 

 part of the island, and in the manner already indicated in the north. 



The Channel We should seek in vain for any evidence of a 

 convulsion of the kind mentioned, which would account for the 

 separation of Britain from the Continent. That problem is like the 

 separation of Ireland from Britain, and requires to be studied along 

 the coast and on the geological map, which demonstrates that the 

 waters which divide these countries are rather analogous to the Bristol 

 Channel, where it separates Wales from Devonshire, than such waters 

 as the Moray Firth or the Firth of Forth. The difference between these 

 inlets of the sea consists in the fact that the former exists in what was 

 an anticlinal fold, while the latter occupy synclinal folds. This anti- 

 clinal fold between Wales and Ireland, and between the Isle of Wight 

 or Kent and France, means of course that the intervening region was 

 thrown into an elevation, which may never have risen from out of the 

 water, but which was essentially a mountain ; and by a well-known 

 principle, familiar to all who know the shape and structure of hills 

 among the old rocks, it has resulted that just where the deposits 

 were 'most uplifted and stretched and cracked, there they were worn 

 away with the greatest ease, and replaced by depressions. The 

 English and Irish Channels are therefore valleys, which have been 

 scooped out in consequence of being thrust up. The rocks thus 

 exposed to the action, first of the sea and afterwards of the atmosphere, 



