Mackintosh — The Sea v. Bain and Frost. 69 



Limited Atmospheric Denudation in the Chalk Districts. — The in- 

 fluence of rain in the Chalk as well as Oolitic districts of England, 

 must be very considerable. But it acts more as a solvent than 

 transporting agent. The matter dissolved is re-deposited.^ It 

 becomes covered with grass, and not one-hundreth part of it ever 

 finds its way beyond the nearest valley or depression. That rain 

 has not altered the general contour of the Chalk districts since their 

 rise above the sea, can be proved by the fact that thousands of raised 

 beaches, many of them only a few feet in height, may be found in 

 Wiltshire, Dorset, and other counties. These beaches generally 

 conform in inclination to the surface of the neighbouring ground. 

 In valleys they often descend very near to the bottom, thus proving 

 that these valleys have not been excavated since the beaches were 

 formed. One of the most remarkable assemblages of these terraces 

 may be seen imdulating along the side of a valley to the east of 

 Mere. On the south-eastern escarpment of the vale of Blackmore 

 they may be seen curving round headlands in successive tiers. 

 These terraces are so intimately associated with the valleys, combes, and 

 escarpments, as to render it evident that all have had a common origin. 



On the Denudation of the Weald. — I think it cannot be doubted that 

 the Weald district of Sussex and Kent has undergone some complicated 

 revolutions since the escarpments acquired their general outline ; ^ 

 and to these revolutions we may partly attribute the obliteration of 

 certain particular traces of the former action of the sea. But that 

 the sea has been there, and that the escarpments are old sea-coasts, 

 cannot be doubted by any one who does not ignore the validity of 

 analogical induction. If we begin with what the sea is now doing 

 at Beachy Head, and then follow the windings of the inland cliffs in a 

 north-westerly direction, we cannot resist the conclusion that they 

 have been shaped by the sea. Beachy Head, and its accompanying 

 combe, may be regarded as a living monument of the denuding 

 power of the waves — the headlands and combes, which stretch into 

 the interior, as dead monuments ; but though dead, they yet speak, 

 in language that cannot be misunderstood by any mind not deaf 

 to the voice of analogy. A great part of the escarpment of the 

 South Downs (to which I shall at present confine attention) consists 

 of a succession of headlands, bays, and combes. The latter point 

 most unequivocally to the peculiar action of the sea. Towards the 

 western boundary of the Weald district many of them have been 

 excavated in the chalk quite irrespectively of any relation hetween soft or 



laying bare the origiaal sea-wom rocks. But in all this we see a tendency the reverse 

 of that ascribed to the atmosphere by subaerialists ; for, instead of rendering more 

 abrupt the inequalities of the earth's surface, it operates in the contrary direction. 

 Among the Cotswold valleys, springs have given rise to landslips (Mr. "Witchell, 

 Quart. Journ. Geol. Soc, vol. xx., Nov., 1864) ; but these landslips can never tend 

 to increase, and far less to originate, the continuous and smooth regularity of a liae 

 of escarpment. 



1 Sometimes the re-deposited Chalk-rubble becomes compact enough to to be mis- 

 taken for Chalk itself. See Mr. "W. Whitaker's paper in Quart. Journ. Geol. Soc, 

 vol. xxi., 1865. 



* See Sir E. I. Murchison's elaborate paper, "On the Drifts of the South-East of 

 England," in Quart. Journ. Geol. Soc, vol. vii., 1851. 



