feet high. of lowland.

These, of course, lose the distinctive character

The mouth of the St Lawrence is, in some respects, analogous. Lowlands accompany it for a great distance from the sea; at Lake Ontario the elevation is only 262 feet. Yet the level tract is narrowed down to a mere border, and does not widen into great lowland plains. The contracted region of low country along the St Lawrence is broken up, too, by rocky heights and riblike ledges, whose absolute height, however, is not to be confounded with the elevation of the plain which they traverse.

In entire contrast are the broad plains of South America, which lie along the course of the Orinoco, La Plata, and Amazon, the so-called pampas and savannas, which extend a great distance into the interior-farther, indeed, than investigators have yet thoroughly prosecuted their researches. In no continent are the distinctions between highland and lowland so sharply drawn as in America. The lowland plains occupy four-fifths of all the country east of the Andes, in South America: only one-fifth is highland; for, notwithstanding the extent of low plateaus and diminutive mountains scattered through these great plains, yet their entire amount is inconsiderable, compared with the immense lowland tracts of that continent. America has fitly been called the region of the greatest depression on the globe, because this is the prevailing characteristic of its whole eastern side, lowlands forming two-thirds of all America, and highlands only one-third.

In Asia, the later hypsometrical observations have shown that the lowlands are by no means so extensive as they were formerly supposed. The highland extends, according to Von Middendorf, much farther north-east of

the Yenisei, toward the northern limit of Siberia and Cape Tchukchee, than was formerly supposed; and the Siberian plain extending westward to the Ural Mountains is narrowed down from 4,079,970 to 2,233,800 square miles. Yet this lowland comprises including central Bokhara or Turkestan, 1,051,200 square miles, and other low Asiatic plains 1,314,000-the enormous area of 4,599,000, or nearly twice the extent of Europe, leaving 9,636,000 square miles for the highlands.

In Africa there are almost no lowlands to speak of, excepting the districts around the mouths of the great rivers indicated a few pages back. To all equatorial Africa this physical feature is entirely wanting. In the north, where the whole Sahara was formerly thought to be one vast low plain, there are now known to be the moderate plateaus already indicated. The area of true lowland is, therefore, sensibly diminished. Vogel's barometrical observations have already shown us that the country around Lake Tchad is about 1200 feet above the sea; the surface of Lake Tchad is 830 feet above the ocean-level, and the lower limit of that region does not, therefore, come within the range already assigned. as the point where highlands become lowlands.

In Australia the lowland seems to be the prevailing physical form, although here and there exceptions to it

occur.

In Europe there are three great lowland plains to be specially mentioned. The greatest, that of middle Europe, embraces the shores of the North Sea and the Baltic far inland, and extends the farthest to the south-east. A second, of hardly less extensive proportions, comprises all northern Russia as far as the White and the Arctic Seas. It embraces but one-third of the great polar

plain, and is really one with the region beyond the Ural chain. The third is the region around the Black and Caspian Seas.

THE MIDDLE EUROPEAN LOWLANDS.

The Germano-Sarmatio-Russian plain extends, without a break, from the mouths of the Rhine, through all central Europe, to the middle Volga and the Ural. It is pre-eminently a region of lowlands, without any elevations of importance, and having no change of level, except very gently undulating swells, and on the north and south margin plateaus which very seldom rise above 500 feet. It begins with the deltas of the Rhine and the Scheldt, in Holland, passes through Lower Westphalia, Lower Saxony, the Marks, Lower Silesia, Lower Galicia, and Poland, as far as the upper Dnieper and the middle Volga. It extends up the Rhine as far as Strasbourg, 474 feet above the sea, up the Weser as far as Cassel, 486 feet, and up the Elbe as far as Dresden, 280 feet.

The true Rhine delta may be defined as lying between Amsterdam, on the sea, and Dusseldorf, 107 feet above the sea-level. Then passing by the broken and romantic tract lying between Dusseldorf or Cologne and Mayence, we come to the true Rhenish lowland, 240 feet above the sea. Münster is 400 feet above the ocean-level. East of the Weser is the Lüneburg Heath, which advances in elevation, as we go toward the Elbe and the Havel, to 300 or 400 feet. Brunswick lies at an altitude of 200 feet; Magdeburg, of 128 feet. The height gradually increases; at Wittenberg it reaches 204 feet; at Dresden 280 feet, where the Elbe issues from the highlands; and

in Lower Silesia we find Breslau, 375 feet above the sea, and its observatory, standing on the hills around the city, at a height of 453 feet, which seems to be the highest point in the whole vast tract.

Between the Rhine delta and the now dry basin of Paderborn, from the Ems to the Weser, Aller, and middle Elbe, is the mountain tract of the Hartz (with the Brocken at the north, 3740 feet high), running up as far as 52° N. lat. By this natural feature the breadth of the great plain is considerably curtailed, as it is also more to the east of the Leipsic basin, from which the Mulde, Elbe, and Elster flow, by the hill country of Lusatia and North Silesia, with the Riesengebirge (Giant Mountains), 5000 feet high, which extends northward as far as 51° N. lat.

A third basin is the Silesian, from which the Oder flows toward the north-west, and enters the southern limits of the great plain near Oppeln and Brieg. A third tract of hill country lies on the east bank of the Oder, and extends to the middle Vistula, the Tarnowitz Heights, in Upper Silesia, about 1000 feet in altitude. The plateau north of the Carpathian range, on which Cracow lies, is 669 feet above the sea; and the most northern hill-group of Kielce, between the Pilica and the Vistula, rises in the Kreuzberg to a height of 1920 feet, and in St Catherine to 2000 feet.

The great lowland advances eastward, with always diminishing breadth from north to south, over the extensive plains of the middle Vistula, at Warsaw, 330 feet above the sea; over the Lithuanian morasses of the Bug; over the Sarmatian district of Minsk and Pinsk as far as Kiev, on the middle Dnieper, at the south-east, and as far as Orsha and Smolensk, at the north-east. Pinsk, in

sea.

the middle of this tract, lies about 400 feet above the The north side of the plain is bounded by the very moderate plateau south of the Valdai hills, at Smolensk, 792 feet high; at Osmana, south-east of Minsk, 882 feet. On the south side it is bounded by the equally moderate plateau of Volhynia and Podolia, whose absolute altitude is yet undetermined, but which, at the source of the Bug, is about 1000 feet.

This is the great Lithuan-Sarmatian plain, which, east of the Dnieper, is transformed into the central Russian lowland, at whose middle point is Moscow, whose exact elevation above the sea is between 300 and 400 feet; at Kazan, on the Volga, the height above the ocean-level is but 270 feet, measuring from the highest point on the banks. Southward, the plain reaches to Simbirsk, 181 feet in altitude. The maximum breadth of this whole vast lowland tract is about 500 miles; the distance between Smolensk and Kiev, and the distance from the central point of the great Russian section to any sea, is between 500 and 600 miles.

THE ORIGIN OF THE GREAT CENTRAL EUROPEAN PLAIN.

The slight elevation of the lowland just described, rising very little above the sea-level, bears, throughout the most of its extent between the dunes of the north and the hill-chains of the south, the character of a formation rescued from the domain of the sea within the very latest geological periods. The almost unbroken uniformity of the surface from the Scheldt to the Volga, about 2500 miles, confirms the character which its geological structure indicates. The disposition of disconnected, superimposed