12 THE HISTORY OF MEDIEVAL EUROPE

Russia is intersected by a network of rivers, some flowing north to the White and the Baltic, others south to the Black and the Caspian Seas. In ancient times Russia was largely covered with swamps and forests, but there were fertile grass steppes then as now in the south. Between eastern Europe and western Asia there is no abrupt transi- tion in climate, flora and fauna, or topography. The plains and mountains of the one fade into those of the other, but the boundary is roughly marked by the Ural Mountains. In France west and northwest of the Alps come other lesser mountain ranges, the Cevennes, Jura, and Vosges; and west of these the basins of the Garonne, Loire, and Seine Rivers, flowing through plains to the sea. From Alps four important rivers, the Po, Danube, Rhine, ; Rhone, flow in opposite directions into as many differ seas, the Adriatic, Black, North, and Mediterranean, from the Alps the land slopes off to the Baltic and North Seas and the English Channel, so on the farther side of those bodies of water — which once, by the way, were for the most part dry land — rise, after an interval of lowlands, the mountains of Norway, of the Shetlands and Iceland, of Scotland and northwestern England and Wales. They face the Continent as the opposite tier of seats rises up in a stadium. It is hardly possible to overestimate the effect of physical environment upon man's life, especially in earlier ages when Influence of tunnels and canals, steam and electricity, had geography not yet overcome and harnessed nature. Once natural boundaries and obstacles could not be so easily disregarded ; and trade routes, race migrations, and military campaigns alike had to follow certain lines. Also man's food and costume and dwelling and industries and artistic creations were dictated to him largely by the ma- terials available in his immediate neighborhood. Fear and appreciation of the forces in nature long influenced reli- gion. Even to-day, if we travel, we find different races and languages and customs and governments and religions in different lands, as well as mines in one region, olive groves