G. On reaching the sea, we find the influence of the river prolonged into the salt-water, augmenting the mass of sediments drifted coast wise by the tide, and feebly assisting in the distribution of them. But the bed of the sea is unequal, soft, or rocky, excavated into hollows, and varied by sand-banks and gravel-beds, not unlike those on the neighbouring land, and even yielding. as they do, bones of gigantic extinct mammalia (Happisburgh coast [and in fact the eastern coast of England from Bridlington to beyond the mouth of the Thamee] ). These points of agreement between the actual sea-bed and the neigh bouring lauds mark some community of origin : the land has been raised out of the sea, and owes some of its irregularities to marine currents (as Buffon thought), or the sea's bed is subsided land. Each of these may be partially and locally true, but there can lio no doubt of the sea-currents having power to alter the distribution of sand-banks and gravel-banks to some considerable, though not precisely known, depth ; and as all the stratified crust of the earth has been once the bed of the sea, it is evident that the action of marine currents is a cause of universal application to the theory of the inequalities of the earth's surface, as well as of extraordinary power.
The slight sketch here presented includes phenomena which may be seen on the English rivers, though not all on one and the same stream : the description may be verified in every one of its stagesa hundred times, and augmented with additional phenomena by any intelligent reader personally acquainted with the physical geography of Britain. Exactly similar phenomena, either all in the same order or variously associated, may be paralleled by instances selected from other parts of the world, and it only remains to apply a plain course of reasoning to them.
The action of atmospheric agencies, river-streamlcts, and rivers, with or without lakes, with or without glaciers, is always one and the same : to degrade the high lands and to raise the low, and thus to equalise the levels, and to diminish the irregularities of the surface of the globe; and this because of tho universal action of gravity, wher ever there are weighty masses and inequality of level. Tho sea's action is similar, and •though complicated by tidal fluctuations, as rivers and lakes are by drought and inundations, and by the variable influence of wind and temperature, its final results are of tho same character.
This is indisputable. It is equally true that tho direction of the existing watery agencies on the land is determined by the present relation of levels between the different parts of the land, and between the land and the sea. Isioreover the effects of these agencies arc perfectly
adjusted to these levels. It follows inevitably that the sum of the effects of these existing agencies has been to diminish the original inequalities of the earth's surface, that is to say, to lower the hills, to smooth and level the valleys, to fill up the lakes, which are a part of the valleys; in a word, to change gulfs into lakes, and chasms into vales, by a mere surface action on forms which had been more boldly marked in earlier eras of nature.
We must therefore believe that immediately after the desiccation of the land, its grand chains of mountains and long continuous vales were more firmly outlined, more roughly and strongly modelled, deeper and higher than they now appear, and it only remains to inquire to what known geological causes this can be justly ascribed.
We must remember, first, that the surfaces of stratification on the sea's bed were once continuous, but on the land they are now inter rupted by excavated valleys and left dismembered on residual hills : secondly, that these surfaces were plains or nearly so, and horizontal or nearly so ; but now they are found contorted, ruptured, placed in angular positions, vertical, or even reversed in particular regions. The latter class of effects depends on the violent nature of the elevating movements to which the land was subject ; the former is often inde pendent of local disturbance, and seems to be due to the mere action of powerful currents of water. But it is often seen that the line of these valleys is the line of a fault, of a synclinal basin, or anticlinal ridge, that is to say, a line of weakness, a line of least resistance, deter mined by causes anterior to the current of water which, flowing up or down the line, or both up and down, has worn it into a valley.
Now if we remember that the most powerful mechanical action of water takes place on the seacoast ; if we remember that, by the con tinual or the periodical rising of the land, this littoral action has been transferred from point to point over every part of the area of the land, beginning among the mountains at the source of the present rivers, and successively washing and wasting every part; we shall readily admit in this one universal and powerful agency the principal cause which broke the continuity of the planes of strata, washed away the least resisting and left the hardest parts, and, by successively retiring lines of action, gradually completed the main features of the valleys and hills which had not been previously impressed by violent subter ranean movements.