formation of lakes, and it is well to be cautious, in studying the origin of lake-basins, to bear in mind the many and complicated causes to which they may be due.

These questions belong to the minor features in our scenery. They have been produced by many local causes, and it is impossible here to treat of them in any but a general way.

The influence of glaciers, which are well known to have existed on the high grounds of Wales and in the lake district, has been spoken of, and some of the valleys have been considerably modified, if not to a great extent formed by them.

In limestone districts, as in Derbyshire and Somersetshire, the power of rain-water holding carbonic acid is very great in dissolving the rock and forming caverns, and sometimes, when the conditions are favourable, re-depositing the carbonate of lime in the form of stalactites or stalagmites; or, again, forming a petrifying spring and encrusting leaves, shells, and other objects with a deposit of tufa. It has been supposed that some of the dales and ravines may originally have been caverns. Be this as it may, the action is the same-these limestone combes and dales have been formed by running water, assisted, no doubt, by the mechanical action of frost, and the chemical action of carbonated water.

We may here also call attention to what is really a very minor point in connection with scenery, but which yet has many points of interest in connection with physical geography.

The origin of certain small holes and excavations in limestone rocks has given rise to much discussion. The atmosphere, pholades, and land snails have severally been called into account for them, and from the observations that have been made, there seems to remain little doubt that all three agents share in boring and burrowing into rocks. By far the larger number of holes and irregular cavities on limestone rocks are undoubtedly due to atmospheric wear and tear, but there are certain small holes more or less regular in shape, about which discussion has taken place. Some are, doubtless, bored by pholas, which can pierce almost any rock, but these burrows are of a pear-shaped or pyriform character, and need hardly be mistaken, although there is no reason to doubt that the atmosphere could mimic these forms, so varied are the shapes it has fashioned. There are other holes, unlike pholas-burrows, and occurring in situations where it would seem that meteoric agencies had no play, which have been attributed by the Rev. T. G. Bonney and Mr. J. Rofe to the action of our common land-snails.

Long ago Dr. Buckland, and subsequently M. BouchardChantereaux, advocated the boring powers of snails, but their views appear to have met with little credence. Mr. Rofe argues very ably for snail-action. The odontophore of the gasteropods,

a cartilaginous strap, bearing a long series of teeth, is capable of a rasping or scraping motion, and this tool he thinks quite capable of producing small cavities in limestone rocks. At the same time, it must be observed that we want more positive proofs of the boring action of snails.

There are some other minor features which deserve a passing notice. The occurrence of large masses of loose rock may be due to the jointage of beds and their being weathered out in situ. Other rocks may jut out naturally and be weathered into fantastic shapes, and not only pluvial action may influence them, but in some cases wind carrying sand has exerted great power in furrowing or in polishing rocks.

Most of the palæozoic rocks, and the igneous rocks and granites, jut out here and there on the hill-sides, and form often a rough barren country, when they yield little or no soil. Large blocks of stone may also have been brought from a distance by a glacier or iceberg and so deposited.

It may be thought that the effects of the sea have been rather neglected in this sketch, but it is by no means wished to detract from its power. The shape of the British Isles is in a great measure, although not entirely, due to its action; the irregularities being for the most part produced by the alternation of hard and soft rocks, the former constituting the headlands, the latter the bays. The effects of submergence have in some cases allowed the sea to encroach and modify valleys previously formed by river-action. This action, as we have noted, tends to check the denudation by rivers. While, on the contrary, a fact pointed out by Professor Geikie, "as the land rises the cliffs are removed from the reach of the breakers; and a more sloping beach is produced, on which the sea cannot act with the same potency as when it beats against a cliff-line;" and this action promotes subaërial denudation.

The set of the tides and currents will tend to influence the configuration of the coast-line and promote the travelling of beaches. In some cases the flow of rivers is checked or diverted for a distance by this action. This is notable on the south coast of England, between Exmouth and Portland. The origin of the Chesil Bank forms an interesting study, and, indeed, requires special explanation. Its isolation from the mainland, according to the researches of Messrs. Bristow and Whitaker, is due to the subsequent subaerial denudation of the land which intervened, and which area is now occupied by the Fleet.

Hillocks of blown sand are produced where there is a great expanse of sand at low tide, subject to the influence of the prevalent winds blowing inland.

In summing up the causes of denudation and their effects upon scenery, it may be remarked that there has been a great

tendency to extreme views, and particularly in attributing too much to marine action.

We have seen that the effects of elevation and disturbance are not unimportant; that, indeed, in the first place they gave the plan to the denuding forces; rents and fractures, even faults -all have in some way influenced the minor features, while the dip of the strata and the texture of the different rocks have likewise affected the configuration of our land. In this respect the angle of repose is important, and may well be studied in our railway-cuttings.

Professor Geikie has compared the work done by rain and rivers, and that done by the sea. It has been estimated that the Mississippi carries annually to the sea about 812,500,000,000 lbs. of mud! Allowing the sea to eat away a continent at the rate of ten feet in a century, and that on a moderate computation the land loses about a foot from its general surface in 6,000 years, then, before the sea could pare off more than a mere marginal strip of land, between seventy and eighty miles in breadth, the whole of Europe would be washed into the ocean by atmospheric denudation.*

This estimate seems to do bare justice to the sea, but it is evident, as Professor Geikie remarks, that the extent of land exposed to subaërial or meteoric agencies far exceeds that exposed to the influence of the sea.

All agencies, however, act in concert; the landslip caused by rain and frost and the dip of the strata is removed by the sea, and the deposits formed at its bottom are upraised and returned to it again by rain and rivers. Thus we find that the whole plan of Nature is one of constant creation and decay. Man has done much to check the wasting action of the sea on our coasts by the erection of groynes and other defences, while by the cutting down of forests he has lessened the rainfall, and consequently diminished the effects of subaerial denudation. Nevertheless, his power has been but feeble in the history of our planet, while his time on earth has really been but a moment compared with the long ages of geological time. And yet the history of each rock, if we consider Man as the ulterior object of creation, has not been one of chance or without design, when we look to the important benefit that they have conferred upon him by the various economic purposes they serve. Nor is the influence of our scenery to be looked upon as accidental, for what more powerful influence for good is there upon the mind of man than the contemplation of a beautiful landscape, and in learning from it something of the wondrous works of Nature as exhibited in the history of our rocks?

"Trans. Geol. Soc. Glasgow," vol. iii. p. 153.

67

REVIEWS.

THE GERMAN ARCTIC EXPEDITION OF 1870.*

VERYONE who is at all interested in the proposed Arctic exploration

EVER

for which our Government are at the present moment preparing, should read the graphic account of the recent expedition of the German explorers, which has been so well related by Captain Koldewey and his several junior officers, and so well translated into English and edited by the Rev. L. Mercier, M.A., and H. W. Bates, F.L.S., of the Geographical Society. It must be confessed at first that the results of the expedition are somewhat small, that is, as regards the amount of discovery either in the domains of geography, biology, or physics; at least, if we are to regard the present work as a faithful and full narrative. Still, as an historic account of the grave disasters suffered, and the patient determination of the men to bear with all risk and danger in making their way to the extreme latitude of 77°, it cannot be excelled. When to this we add that in point of excellence and number of engravings it is almost unsurpassed, that the book is simply one mass of illustrations, some of them exquisitely coloured, we shall have said enough to urge our readers immediately to possess it.

The general facts of the expedition may be brie¶y summed up as follows: On the 15th of June, 1869, the two vessels, the Germania, a steamer of about 600 tons, and a small schooner, the Hansa, left Bremen haven, in the presence of the King of Prussia, Prince Bismarck (then Count von B.), General von Moltke, and others, and were towed out of harbour by a couple of tugs. In the evening they fairly started on their journey northwards, their intention being to explore the east coast of Greenland as far as latitude 77°. It was originally thought that both vessels could keep together throughout the voyage. However, fate decided otherwise. The two vessels some time in July lost each other for a few days as they approached the ice. The loss was followed by a reuniting, when the crews of both were excessively rejoiced at the result. They parted company, however, the next day, and never met together again, and this was on the 20th of July, after mid

"The German Arctic Expedition of 1869-70; and Narrative of the Wreck of the Hansa in the Ice." By Captain Koldewey, Commander of the Expedition, assisted by Members of the Scientific Staff. With numerous Woodcuts, Maps, Portraits, and four Chromo-lithographs. Translated by the Rev. L. Mercier, M.A., and Edited by H. W. Bates, F.L.S., Assist. Sec. Royal Geographical Society. London: Sampson Low & Co., 1874.

night, and when they were already in latitude 75°. This was the highest point to which the Hansa reached. Following this vessel alone now, we are told various tales, all of which record the extreme cold, the violent storms, and the various efforts made by the men to manage this extremely small and, we should think, unsatisfactory vessel. We do not think that the captain, Herr Hegemann, left anything undone which could have saved her. However, it was in vain. The vessel lay in a mass of ice; great blocks, many of them higher than her deck, surrounded her; and of course, under the combined pressure of the ice and her weak condition (she was not ironbound, as was the Germania), she eventually became so leaky that the captain saw she must become a total wreck. Here was a condition! The crew had, of course, to leave the ship, which was fast sinking, and to set up a home of some kind in the huge wilderness of ice in which they were, and which was simply and solely the frozen ocean. What an awful condition to be reduced to! Yet they all bore it bravely. They set to work with a will, getting as many things as possible overboard, but still compulsorily allowing a considerable quantity of coal and other materials to remain within the sinking ship. At last they had got all they could collect from her on to the ice, and they saw her go down beneath it, with the great bulk of all their scientific apparatus and natural history collection. Their lives were nɔw utterly unprotected, and from this period-night between October 21 and 22-they remained residing upon and carried southward with the ice till May 7, 1870. Now this period is full of adventures of all kinds, and it is faithfully and well described in the pages of this volume. They, of course, saved their boats, and in these, having abandoned the floe, they travelled south to the island of Illindlek, which they reached on June 4, 1870. On June 13 they arrived at Fredericksthal, where they stayed some time, making a series of excursions, and from which they were eventually taken by a small vessel to Copenhagen, whence they reached Hamburg on September 3, 1870-a time when, indeed, they must have been struck with wonder and astonishment, for on that day the news of the mighty battle of Sedan flew over nearly every civilised country in the world, and must unquestionably have astounded these patient explorers who had travelled from the polar world. Thus ended one part of the expedition.

The explorations of the Germania were, as we might have expected, from her better build, larger size, and steam appliances, infinitely more successful. In the first instance we may state that the Germania reached a latitude as high as 77°, being, in point of fact, considerably north of Cape Bismarck. Very interesting are the descriptions of the scenery, and the admirable plates, some coloured, that occur in this part of the volume. The explorers, of course, did not do very much during the earlier part of the winter, for they were obliged to harbour their ship at Sabine Island, and build a series of walls of ice around her, to protect her hull. Then follows a long account of the various occurrences and pastimes by which the ship's crew managed to pass through the depths of winter; and this account of the period during which the days and nights were completely given up to darkness is interesting in the extreme. About the beginning of March, however, the explorers thought of going further north, and so they set out with a sledge, which, in the absence of dogs, was drawn by themselves for more than three