THE ORIGIN OF SCENERY.
riEaddress of the President of the British Association may be said to give the key-note to the proceedings of its annual meetings. No doubt the ordering of the sections and sub-sections is ruled by an anxious desire to give fair- play to all possible forms of discussion of all things terrestrial and things celestial, which can be brought under the heading of "Science," with the possible exception of "Psychical Research," which engaged the attention of a select band of enthusiasts just previous to the meeting of the British Association. But the general public have become accustomed to look to the Presidential address for a clear and concise statement of the present state of knowledge in the branch of science on which he is presumed to speak with authority. The attitude of the German philosopher in reference to the request of a Parisian interviewer for a short statement of his system, that his philosophy " could neither be expressed shortly, nor in French," is impossible for a President of the British Association before an audience of his exacting fellow-countrymen. His speech must be reasonably short, and however abstruse the terms appropriate to the subject, it must for this once be expressed in a tongue understanded of the people. It is obvious that from this point of view, geology has an advan- tage over astronomy as a subject for the Presidential address. Sir Archibald Geikie, in his review of the history and position of the science of geology, had not, like his predecessor, Dr. Huggins, to assume the possession by his hearers of a familiarity with the principles and problems of the higher mathematics, and of the laws which govern the movements of the Solar System. His subject, moreover, is one which, with the exception of the early and temporary disagreement between the followers of Hutton and Werner, has roused singularly little conflict of views between its most ardent students, and so lends itself naturally to a clear and consecu- tive history of its progress during the century for which it may be said to have been the object of serious inquiry. Complete unanimity seems now to exist among geologists as to the fundamental doctrine which Hutton evolved just a hundred years ago, that in the changes now in progress on the earth's surface must be sought the explanation of those which occurred in former times. Of the natural agencies and natural tools which Hutton rightly con- ceived to be the means by which those changes were, and are, effected, no one has written more clearly, or with greater interest to the general reader, than Sir Archibald Geikie himself. His reiteration of Hutton's belief that "every portion of the surface of the mainland, from moun- tain-top to sea-shore, is continually undergoing decay and travelling towards the sea," is now supported by familiar examples and details of the work of rain, rivers, ice, and frost, giving to the theory that reality which a right explanation of facts always visible but never understood, supplies. The - working-out of the Huttonian theory is perhaps the best example of the old fable of "Eyes and No Eyes 'extant. That it should not have taken place earlier, is not surprising. There was a kind of sentimental conspiracy against truth in this par- ticular region of inquiry. The idea of mighty convulsions of Nature, taking place at remote periods and forming moun- tains and chasms in a day, was far grander than that of the gradual carving-out of hills an4 valleys by rain and rivers. There was a certain indelicacy in the notion of asking a moun- tain its age, and telling it, so to say, by looking at its teeth. But the new geology went further. It not only proposed to judge the age of the mountains, but boldly claimed to set a limit to the duration of the "everlasting hills." If the theory were true that all the earth's surface, mountains and plains alike, is being gradually washed down to the rivers, and deposited as sand and mud, it was clear that the hills were no more eternal than the plains. But the Hnttonian theory, while prophesjing
• the change of form of the earth's surface, set no limits to the duration of its matter. The slowness of the processes by which the changes are effected oppressed the mind with the idea of their infinite antiquity and boundless duration. These surmises as to the extent of "geological time" are among the few theories of geologists which seem to have afforded cause . for recent controversy, since the first shock given to the old
• belief of the limit of six thousand years to the earth's existence was forgotten. Sir Archibald Geikie acknowledges he debt which geologists owe to Lord Kelvin for "reducing the estimates" on which they were reconstructing the history of the globe. His calculations have shaken to pieces the theory that "neither among the records of the earth, nor in the planetary motions, can any trace be discovered of the beginning or of the end of the present order of things." "The rate of loss of the earth's heat," Lord Kelvin declares, must set a limit to its antiquity," while "every lineament of the Solar System bears witness to a gradual dissipation of energy from some definite starting-point."
But when estimates dealing with hundreds of millions of years are in question, the enthusiasm of ordinary minds is apt to flag. A far more interesting side of modern geology is the explanation which it offers of the origin of natural scenery. Sir Archibald Geikie reserved the consideration of this, which he justly termed "one of the most interesting and fascinating -departments of geological inquiry," for the close of his address. He would have done well to have remembered the warning of Hugh Miller,—that "it is always perilous to attempt connecting new associations with old scenes." It is the ever-present temptation of the geologist to "get under the skin-deep beauty of the landscape," and penetrate into regions which for our day have far less interest than the actual contour of the earth as we see it. The living interest -of geology lies not so much in what the President of the British Association calls "visions of long-lost seas and lands rising before us in a long-retreating vista," and what the author of the Book of Job called "waters forgotten of the foot, and dried up and gone away from men ; paths which no fowl knoweth, and which the vulture's eye hath not seen," as in the cause which made this hill and that river. Take, for instance, the view which Cobbett saw from Hawkley Hanger, above Selborne :—" I pulled up my horse, and eat and looked ; and it was like looking from the top of a castle down into a sea, except that the valley was land and not water. From the south-east, round southward to the north-west, the main valley has cross-valleys running out of it, the hills on the aides of which are very steep, and in many parts covered with wood. The hills which form these cross-valleys run out into the main valley, like piers into the sea. The ends of these promontories are nearly perpendicular, and their tops so high in the air, that you cannot look at the village below without a feeling of apprehension. The leaves are all off, the hop-poles -are in stack, the fields have little verdure. But while the spot is beautiful beyond description even now, I must leave to imagination to suppose what it is when the trees and hangers and hedges are in leaf, the corn waving, the meadows bright, the hops upon the poles." Cobbett does not sneer at the surface beauty of the landscape for being " skin-deep ; " but he does show a strong feeling for the form of the hills and valleys ; and his very words seem to invite some explanation of that form. That feeling is a very general one in face of picturesque natural scenery, and for much of its variety geologists can now offer an ex- planation. English scenery—the familiar contour of the valleys and hills of our Home Counties—is almost entirely the work of rivers and rain. These tools are at work everywhere; the charactetistic differences of scenery are due mainly to the material on which they work. The soft, rounded outlines of the chalk hills are due to the uniform decay of a homogeneous substance exposed to rain above and to collected waters be- neath. The water which dissolves and wastes away the sur- face, also sinks into the chalk, and there dissolves it from below, forming the hollow "punch-bowls" and combs so com- mon in the Downs. The surface decay of gravel and sandstone is more rugged and partial, giving to the Surrey hills their broken faces and abrupt, precipitous sides. Other natural features seem uniform in all but the most rugged districts. Fair, level meads fringe all rivers alike, except the hill-streams of the stony uplands. They form the natural and appropriate accompaniment of river scenery. , To the geologist, they seem also its necessary accompaniment. For when the stream rises in flood and overflows its banks, the current, as it slackens in pro- portion to its overflow, deposits the mud and earth which it bears. Where the flood is deepest, there the more earth falls ; where sluallowest, there is the least deposit. So that in time, however
• shdving the surface on which the flood-water lies, its tendency
is to make a level mead. In the limestone and marble districts, the rivers take to themselves chisels and hammers fit for the substance on which they have to work. In the Yorkshire dales, the process which cut out the rugged sides of the lime- stone bills may be read in the bed of every tiny beck which flows into the main stream. The round boulders, reduced to half the" weight" when carried in the water, are dashed against the sides, and cut out thousands of chips as if with a rounded gouge, or scoop holes like augurs, as the water spins them round in rock as hard as these primitive tools. In Scotland, especially in the Highlands, where natural scenery exists on a bolder and more imposing scale, the same processes and the same tools are at work. But to these must be added the work of prolonged frost and snow on the high mountains, and the work performed by vanished glaciers, the demolition of the ancient forests, and the drainage of the fens and peat-mosses. With the exception of the glaciers, all these agents may still be observed, and the agreement in detail of their several pro- cesses watched and compared. Some such knowledge seems now a necessary acquirement for the lover of natural scenery unless he is prepared to regard the contour of the landscape as sufficient in itself, and to be accepted like the shapes and colours of clouds, as in the main fantastic, and without reference to the past or future.
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