layers, running to a great depth, is exactly similar to that which we know results from the action now going on at the bottom of shallow seas. And in the great central European plain there is no sharply-defined geological limit met at the border of the North and the Baltic Seas. The same features extend beneath the surface of both of those seas. This whole lowland is, therefore, to be regarded as an immense basin, now dry, but once the bottom of a great sea,—an extension of the seas which now form a part of its northern border. The old coasts are now seen far inland. Wherever this coast-line changed its course, the whole landscape now alters its appearance ; and yet more striking than the external view is the internal constitution of the soil. Masses of stone, standing out in full view, reveal the inner structure of what lies concealed. And these rocky projections are precisely analogous to the jagged outlines of our present bold seashores. The land is not cut up by inlets hollowed out by the action of waves and currents to a considerable depth, yet traces of such movements, and of the physical formations effected by them, are found. Promontories and islands are now found in plateaus, and hills encompassing dry basins. To the latter belong the inter-vale of the Rhine, and the basins of Paderborn, Leipsic, and Silesia. To the former belong the hills and plateaus of middle Germany; of the Westphalian Mark, from Elberfeld to Dortmund, or, as might be said, from the Ruhr to the Lippe; the Teutoburg Forest to the Weser; then the Weser Mountains, and the Hartz to the middle Elbe; the Thuringian Forest and the Erz Mountains around the Leipsic basin to the upper Elbe; the Lusatian Mountains and the Riesengebirge to the Glatz Mountains, on the upper Oder; the Trebnitz Heights of Silesia, and the

lower plateaus of the Fore Carpathian range, embracing Cracow as far as the hills of Kielce and the confluence of the San with the Vistula. Along the southern border of the ever-broadening plain are the plateaus of Galicia, about 1000 feet in height, of Volhynia and Podolia, and then less elevated plateaus, till we reach the Dnieper.

The geological character of the border of the sea which once covered what is now central Europe, is full of interest, because from it can be deduced all that we can know of the history of those great changes.* But we must pass over this, and only indicate the geographical configuration of the dry basin as it exists now, and forms the great Germano-Sarmatio-Russian plain.

In the course of previous remarks on the lowest range of plateaus, I have observed, that along the south coast of the Baltic the moderately elevated hill-chains of Pomerania and of Old Prussia separated the true coast with its lowland from the great interior plain, forming a barrier, averaging about 300 feet in height, with here and there a form which runs hard upon the lower limit of plateaus of the second class; at any rate, a transition between the lowland and the plateau.

It may here be remarked that the long, low chains, made up mainly of loose sand and other mixed and uncombined materials, and running along the southern border of that band which skirts the Baltic, seem to be dunes once running along the shore of a sea which has now receded many miles to the north. In the deep channels and old inlets now dry, as for instance in the great break through which the Vistula passes below Thorn, only loose breccia, and no united layers of stone,

* See Fr. Hoffman's 'Uebersicht der orographischen und geognostischen Verhältnisse des nordwestlichen Deutschland,' Introduction.

Yet this does not seem to be the case everyappear. where, although in the Cis-Ural and Baltic depressions dune-like ridges are to be found, some of them rising to a height much greater than was formerly suspected. These, it is true, are scattered, and only partially prevalent, but here and there they ascend to an altitude of nearly 1000 feet. At the eastern end of the great Pomeranian sea-plain west of Dantzic, and between that city and Bütow, where the sand ridge, which formed the ancient shore-line, runs very far to the north, there are a number of villages 400 feet above the sea. The Lower Mountain (Thurmberg), 54° 13′ 29′′ N. lat., rises to a height of 1024 feet; the hill near Upper Buschkau, east of the Thurmberg, is 814 feet high; the hill near Hulterfeld, 846 feet; and the Höckerberg, near Schönberg, 902 feet.

Of the Thurmberg, Humboldt remarks that it is the most remarkable elevation between the Hartz and the Ural Mountains, and that only a few points in the Valdai range can be brought into comparison with it. Its position close by the sea is especially noteworthy. It is very probable, according to Humboldt's opinion, that those inequalities of surface, formed of sand once partly or wholly submerged found in Mecklenburg, Pomerania, East Prussia Proper—and now divided into flats and hillranges, do not belong to the dune system of the ancient shore-line, but have originated by ordinary upheaval; in the formation of limestone, and of the usual Jurassic rocks, which, afterward, have been covered with sand and other loose materials. The peculiar accumulation of genuine marine fossils indicates the existence of upheaved rocks below the upper layer of sand.

It is these elevations which in the constantly advancing

ridge or ridges run north-easterly, and take the form of plateaus, increasing in breadth from the watershed north of Smolensk, and the source of the Dnieper, in the Valdai Forest, and the western Uwalli, and which are found between the Volga and the Dwina, and thence run eastward as far as Perm, on the Kama. They form the line of demarcation between the great central European plain and the north Russian lowland, which extends as far up as the Arctic. This easterly chain, so far as it has been measured, seems to be less in altitude than the Valdai hills, which are about 1000 feet high. In East Prussia Proper and Livonia there are elevations of more than 600 feet; about 55 miles south of Dorpat Munnamäggi, the point of culmination, according to Struve, is 996 feet above the sea; south of Vilna the heights of Puzewitch reach an elevation of 990 feet.

In the same direction, still north-east, runs the Valdai, forming the source of a number of large streams and the great watershed of eastern Europe. On the road from St Petersburg to Moscow, Humboldt found the altitude at Nowaja Ijetza 660 feet, and the highest point at Popowa Gora 792 feet (according to Pansner, 876 feet). One point going south from the Valdai, at Mosti Derewna, the latter naturalist has ascertained to be 1032 feet above the sea; and the highest point in the range is, according to Helmersen, 1098 feet. Still further eastward, between the Valdai hills and the lake region between Lake Seliger and Bielo Osero, the range of uplands, known as Uwalli, running north-westerly, intersected by numerous canals, and forming the watershed of a number of rivers, gradually diminishes in height, but, still advancing eastward, it rises again, in the neighbourhood of Perm and the Kama, to 1014 feet-about the elevation of the Valdai

range. Uwalli is only the Sclavic name of such hills as those whose absolute height is insignificant, but which, crossing as they do the great plains of Poland, Lithuania, and Russia, were formerly confounded with mountainranges, and were so represented on the maps. They have, of course, great hydrographical value, and play a leading part as the watershed of eastern Europe.

THE PONTO-CASPIAN PLAIN, THE GREAT DEPRESSION OF THE OLD WORLD.

This second vast lowland is the direct continuation of the central European lowland, with a decided sinking toward the Black and the Caspian Seas, indicated by the course of the rivers of that region. It extends from the mouth of the Danube over the lower Dniester, Bug, Dnieper, Don, and Volga, as far eastward as the Sea of Aral. To the last named the Siberian plain gradually declines. The southern plain of Europe stands in unbroken connection, so far as its formation is concerned, with the West Siberian plain (2,213,400 square miles in extent), and is, therefore, one of the most extensive lowlands on the globe. The Baltic-Sarmatian plain is separated from the West Siberian merely by the long Ural chain (from 50° to 67° N. lat.), whose elevation is only from 4000 to 5000 feet, and whose breadth is unimportant. Take away the Ural, and a continuous line could be drawn from Breda, near the confluence of the Meuse, Rhine, and Scheldt, across Europe and Asia, following the line of 50° N. lat. as far as the Chinese frontier, passing over a continuous series of low, insignificant hills, heathlands, and steppes, and traversing a space esti

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