64 Mackintosh — The Sea v. Bain and Frost. 



tains, wMle mountain-systems have been archipelagos and archi- 

 pelagos mountain-systems. If we take a detailed chart of an archi- 

 pelago, and compare the depths obtained by soundings, we shall find 

 a striking correspondence between its inequalities and those of an 

 elevated mountain-system.^ 



The Sea not a levelling agent. — That the sea, regarded as a denu- 

 dating agent, does not now tend to plane down the land, can, I 

 think, be easily shown ; for on coasts and among islands exposed to 

 the action of currents and the fury of storms, it is continually forming 

 coves, headlands, bays, creeks, straits, etc. Mr, Jukes admits that 

 the sea can excavate gaps or passes on the crests of islands, and that 

 marine denudation is effective about the sea-level;* but this dis- 

 tinguished geologist leaves out of consideration that the land has 

 risen and fallen so as to enable marine denudation to be effective 

 at all altitudes. The sea, by assailing coasts at different levels, may 

 be said to have the land more completely at its mercy than any 

 agency which oscillates with the land. But even at a stationary 

 level the sea can bring cliffs several hundred feet high within its 

 direct influence, while cliffs more than a thousand feet high are often 

 subjected to its undermining sway. 



The sea can form the most abrupt inequalities along its coasts 

 during intervals between sudden elevations and depressions ; and a 

 succession of such lines or tiers of inequalities, each consisting of 

 vertical cliffs,^ caves, coves, creeks, bays, promontories, and straits, 

 would certainly not constitute a plane of marine denudation. I 

 believe that most of the inequalities of Great Britain (so far as thej'' 

 are not the result of dislocation, elevation, depression, or subsequent 

 glacial action) are unequally upheaved sea-coasts ; and that while 

 rivers have increased these inequalities, rain and frost have tended 

 to reduce them. 



Bain and Frost incapable of producing Cliffs. — The subaerialists 

 would seem to contradict themselves in making frost and rain at one 

 time a demolisher of the cliffs of river-gorges, and at another time a 

 former of escarpments remote from rivers. Excepting in a case of an 

 easily-eroded under stratum already exposed by marine denudation, 



1 Admitting that the inequalities of sinking archipelagos were partly formed by 

 ancient subaerial causes, the sea would have an undoubted claim in the case of archi- 

 pelagos which are gradually rising. But the advocates of atmospheric denudation 

 cannot consistently appeal to submarine inequalities, as according to their theory the 

 sea ought to reduce these inequalities previously to the area they occupy becoming 

 dry land. 



2 Quart. Journ. Geol. Soc, vol. xviii., p. 391. Among the Shetland Islands the 

 sea is now giving rise to a series of the most abrupt inequalities. The coasts even of 

 the mainland are singularly irregular and broken, being indented with innumerable 

 arms of the sea, called voes, which penetrate into and intersect the interior parts of 

 the island in such a manner that, in traversing it, a traveller cannot find himself, at 

 any one point, farther than three miles from one of these voes, or from the open sea 

 (Penny Cyclopsedia, "Shetland"). Among the Faroe Islands, the land close to the 

 sea consists in general of perpendicular rocks, from 1200 to 1800 feet in height 

 (ibid., "Faroe"). 



3 Fac-similes of the highest and steepest inland precipices may be seen on our 

 present sea-coasts. 



