and Niemen flow to the northwest, and the Ural, Volga, Don, Dnieper, and Dniester to the south. The distribution of rivers in the western part is more complicated. Each of the five chief outlying members of the continent (the three southern peninsulas, Scandinavia, and the British Isles) has its own river system. In the continental mass the slopes from the mountains to the low plains north and south of them give direction to the river courses. The Vistula, the Oder, the Elbe, the Weser, the Rhine, the Seine, the Loire, and the Gironde follow the slope to the north and west; only the Rhine, of all these rivers, comes out of the Alps. Three rivers are exceptions to this rule; for the Danube, rising in the German Mittelgebirge, the Po, and the Rhône, rising in the Alps, do not flow directly away from the mountains, like the northern river, but along their edges or near them-the Danube and Po to the east and the Rhône to the west and south.

The rivers of Europe offer extraordinary advantages for commerce, although the two largest of them, the Volga and the Danube, empty into inland seas the Volga into the Caspian, which has no outlet, and the Danube into the Black Sea; none of the great rivers is impeded by cataracts as in Africa, and their upper courses are not situated on table-lands of enormous height, unfavorable for development, as in Asia. But the rivers are so grouped that it has been possible, with the aid of comparatively short and easily dug canals connecting them, to make continuous waterways in various directions across the continental mass. Thus, freight boats ply through the land from Bordeaux to Cette, from Havre and Rotterdam to the mouth of the Rhône, from Amsterdam to the mouth of the Danube, from Danzig and Riga to Kherson on the Dnieper and thence to the Black Sea, from St. Petersburg and Archangel to Astrakhan on the Caspian. The longest river and canal routes of Russia are those connecting the Caspian Sea and the Arctic Ocean, the Caspian and the Baltic, and the Black Sea and the Baltic. Boats loaded on the Vistula in Russia may be sent direct, by inland routes, to all the ports of north Germany, and the Netherlands, Antwerp, and Havre. The importance of the Volga and the Danube, while very great locally, is diminished by the fact that they flow towards Asia and away from the great centres of commerce. of the Mediterranean rivers are small and of little commercial importance; even the large Rhône is too shallow for the highest usefulness. The rivers of the Atlantic watershed, including its tributary northern seas, are those that have had a profound and far-reaching influence upon the development of the world's ocean trade.

Most

Fresh-water lakes are particularly numerous in three regions on the Swiss plain between the Alps and the Jura, in the British Isles, and in a wide territory bordering on the Baltic in Scandinavia and northwestern Russia. The largest are on the east and south of the Scandinavian mountains, the Ladoga and Onega of Russia being the greatest of Europe's sweet-water lakes. The largest number are in Finland. These northern lakes were formed by the ancient glaciers, which left the marks of their passage deeply graven in the surface of the land, forming many lake basins. As the Swiss region has also been extensively glaciated, the high valleys still retaining the ice streams, it is one of the important lake regions. Nearly all the larger

Geology. Broadly speaking, Europe may be divided into three principal regions: 1. To the northeast of the Carpathians, the chief characteristic of the geological structure of Russia is the almost horizontal position of the sedimentary beds. In other words, the plications and dislocations of the rocks that mark the geology of the south and west are for the most part lacking in eastern Europe. 2. The south of Europe, including the Alpine system, is a region of great plications, relatively recent (the tertiary period), with elevated mountains. 3. The rest of Europe, from Bohemia to Spain and Scandinavia, shows ancient massifs plicated in the Archæan epoch, whose inequalities of relief have been largely modified by erosion. These primary massifs are separated by large areas of mesozoic and tertiary beds (the low plains), that in general are not plicated.

The geological structure of the mountain systems is varied and complicated. The Alps are composed of a granite nucleus with stratified beds, greatly faulted and folded, upon their flanks. The Jura is composed mainly of limestones, simply folded, with subsequent erosion. The Pyrenees, on the north boundary of Spain, are also of folded stratified rocks, as are many of the ranges traversing the plateau of the Iberian peninsula. The Apennines, one of the most recently formed ranges of Europe, is composed largely of Tertiary beds, much folded, the folds being arranged en échelon. In the south the Carpathians and Balkans are composed of a central nucleus of metamorphic schists, with stratified limestones upon their flanks. The Ural Mountains are of crystalline rocks. The mountains of the Scandinavian peninsula are of great age, being in large part Archæan with granites and schists, while down the slope towards the Baltic more recent formations successively appear, and in the southeast Triassic, Jurassic, and Cretaceous rocks are found. The great plain of Europe is floored by Cretaceous and Tertiary beds, except in Finland, where Archæan rocks, stretching across from the Scandinavian peninsula, cover the land. The mountainous portions of the British Isles are chiefly composed of granites and schists, while the lowlands are floored in great part with Jurassic beds. The northern half of Europe was in recent geologic time covered by a great ice sheet, which in its retreat has covered the land with glacial deposits, besides having by its erosion greatly modified the surface, changing the courses of the streams and scouring out lake basins. The soils of this portion of Europe are in great part composed of glacial silt and detritus, transported by this great sheet of ice.

Carboniferous coal deposits have been found in many parts of Europe between the parallels 40° and 60° N.; in eastern, southern, and west central Russia, Austria-Hungary, Germany, Belgium, France, Spain, Scotland, England, and Wales. Those of England and Wales are of special value and importance; the proximity of the English coal mines to the sea and the leading coal-buying countries make England the

greatest coal exporter. The rich distribution of iron ores, together with the abundant occurrence of coal, gave Europe its manufacturing su premacy. Great Britain, mining coal and iron in the same or adjoining fields, produces about one-half of all the pig iron of Europe, drawing also, like Germany, upon the superior steelmaking ores of Spain and Sweden. Nearly twothirds of the iron of Germany comes from the mines of Alsace-Lorraine and Luxemburg, where iron is closely associated with the coal fields of the Saar. Belgium, mining iron on the coal fields around Namur and Liége, has been called Little England, because coal and iron occur together. The best iron ores of Austria are not found near her coal, and this is true also in France except around Le Creusot and SaintEtienne. Nine-tenths of the iron mined in France comes from the great field around Chavigny and Nancy. Iron is widely distributed in Russia, but many of the mines are not yet connected by rail with the main sources of coal. Germany is the world's largest source of zinc, and the Belgian mines are among the richest in Europe. The tin mines of England are the largest European sources of this metal. Russia supplies about 95 per cent of the platinum of the world. Most of the sulphur used in the industries comes from Sicily and south Italy. Russia is the fourth largest producer of gold in the world, Germany the fourth and Spain the sixth largest producer of silver; Spain and Portugal are, next to the United States, the largest producers of copper, and Spain provides the largest supply of quicksilver and is surpassed only by the United States in lead. Nearly every country produces its own salt, either from rock beds or by evaporating sea water in saline marshes. The Netherlands and Switzerland are lacking in useful minerals, and Italy has no coal to smelt her iron ores.

Climate. Europe is the only continent that lies entirely outside of the tropical zone, and only a small part of it is included in the frigid zone. The ameliorating influences of the north Atlantic and the westerly winds that blow over it are felt far east along the shores of the Arctic Ocean, so that at Katharine Haven, on the Murman coast, the harbor is practically ice-free the year around. Thus, though the continent extends several degrees of latitude north of the Arctic Circle, very little of it is under polar influences. The continent lies in the temperate zone; and of all the land masses in the same latitude it has the mildest and most genial climate. The warm winds from the Atlantic, the prevailing winds, have almost everywhere free access into the interior, sweeping up the arms of the sea and across the low coasts and plains, not only mitigating high and low temperatures, but also giving wide distribution to the rainfall. The fact, also, that the mean elevation of the continent above the sea is very much lower than that of any other continent excepting Australia (only about 950 feet, according to the results obtained by Supan and De Lapparent), emphasizes the prevailing temperate influences. In all parts of the continent there are sufficient warmth and rainfall for agriculture except where farm operations are prevented by cold in the extreme north and in the highest mountain regions, and by dryness on the salt steppes of the Caspian Sea.

The eastern part of Europe, however, is remote from the influence of the sea and has the

continental rather than the sea climate. The mean annual temperature, therefore, declines not only from south to north, but also, except along the Mediterranean, from west to east, e.g., Greenwich, 49.7° F.; Berlin, 48.4° F., Warsaw, 44.9° F.; Saratov (East Russia), 41.7° F.-these four places being in nearly the same latitude. But while the yearly mean of temperature is lower in the east than in the west of Europe, the summer temperature is higher in the east than in the west, because the interior land mass becomes more heated than the regions bordering the sea with their more equable climate. In the south the influence of the Mediterranean is to impart to the countries along its shores a very uniform climate, the Alpine system also contributing to this advantage by warding off the cold northeast winds.

The precipitation decreases with distance from the Atlantic, the eastern part of the continent being much drier than the western, and driest along the north coasts of the Black and Caspian seas, where forest gives place to steppe. In no region, however, is the country so dry as to become a desert. In the northern half of Europe the precipitation is quite well distributed throughout the year, while winter rains predominate in all the Mediterranean countries. In a large part of Spain, e.g., irrigation is the basis of agriculture because most of the rain falls after the growing season. Many local conditions modify both temperature and quantity of precipitation. The Scandinavian mountains, e.g., are the cause of the larger precipitation on the west than on the east side of the peninsula; they also exclude the icy northeast winds of winter from the west harbors of Norway, which are ice-free.

Flora. If temperature be taken as the determinant-perhaps the simplest method in classifying the flora of Europe-three general regions are observed which more or less overlap one another. In general, the limits of these regions vary with the isotherms and with the coast lines, but are modified by mountain ranges and rivers; the summits of the former affording homes to boreal species, the valleys of the latter allowing less hardy plants to extend inland into colder localities than they could otherwise reach.

The Arctic region, mainly tundra, which in northwestern Europe finds its southern boundary on the poleward side of the Arctic Circle, and in the northeastern part of the continent extends considerably to the south of this line, is characterized on its extreme northern border by lichens and mosses, which gradually give place southward to perennials of wonderful hardiness and longevity, but of small stature, slow growth, and inferior powers of reproduction by seed. The mountains throughout the continent present similar gradations, the vegetation at the highest altitude corresponding more or less closely to that in the highest latitudes and disappearing at lower elevations among species of more temperate regions, which gradually supplant it as the altitude is reduced and the temperature consequently increased. By far the most common species of this Arctic flora are the saxifrage, potentilla, poppy, scurvy grass, crowfoot, all of which bear showy flowers; and stunted, trailing junipers, willows, and birches, which are buried under the snow during the long winters. The species of this region, about 1700, are of insignificant economic importance when compared with those of the other two