VALLEYS AND GREAT LEVELS OF THE EARTH. 223 



there can be little doubt that most valleys, from the grand rents of mountain ranges to 

 the wide and gently sweeping hollows of the general surface, are mainly due to internal 

 causes of disturbance, their physiognomy being subsequently modified by aqueous and 

 atmospheric agency. The great depression of Western Asia, embracing many thousands 

 of square leagues, of which the Caspian Sea and the Sea of Aral are the lowest points, is 

 supposed to be intimately connected with the upheaval of the Caucasus, the plateau of 

 Persia, and of High Asia. 



When the valley form of the earth occurs upon a grand scale, there are points at which 

 the traveller loses sight completely of the high lands that environ it. He beholds, 

 stretching out on every side, a tract of level land, or at least the diversity of hill and vale 

 occurs in such an unimportant degree as not essentially to disturb the idea of being in a 

 flat country. The forces which have given such a peculiar character of variety to 

 mountainous districts have only affected, to a comparatively feeble extent, these portions 

 of the terrestrial superficies. In the former, the difference between high and low is often 

 that of thousands of feet in a very small space, while in the latter frequently it does not 

 amount to fifty feet, nor in some cases to ten, through a wide area. The surface rises and 

 falls in gentle wavy undulations, here and there interrupted with bolder features, while 

 occasionally a dead level is exhibited. These tracts may be collectively called plains, 

 using the term in its geographical sense, not as meaning a perfectly horizontal surface, 

 but an extent of generally level country. They are known in the Old World under a 

 variety of names, as heaths, landes, steppes, tundras, and deserts. 



Europe contains an immense extent of low flat land. It comprises part of northern 

 France, the greater part of Belgium and northern Germany, all Holland and Denmark, the 

 Avhole of Poland and southern Russia, thus stretching from the banks of the Seine to the 

 terraces of the Ural and the waters of the Black Sea. This region, in general very level 

 and fertile, traversed by numerous navigable rivers, is the birth-place and surface land of 

 a large amount of modern civilisation. It is a vast plain with two grand declivities, 

 inclining north and south-easterly, which determine the course of the superficial waters 

 either to the Baltic Sea and the German Ocean, or to the basin of the Black Sea. As an 

 instance however of the little inclination of the surface in some places, a prevailing north 

 wind will drive the waters of the Stattiner-Haf into the mouth of the Oder, and give the 

 stream a backward flow for an extent of thirty or forty miles. At the northern confine of 

 the European lowlands, to a considerable distance from the shore, there is only a very 

 slight elevation above the sea, and hence extensive marshes are formed along the coast. 

 Holland is to a great extent so near the level of the waters as to require artificial means 

 to protect it from inundation ; and on approaching it, the trees and spires seem as if 

 planted upon the ocean. Notwithstanding the general fertility of this tract of country, 

 we meet with many spots incapable of cultivation, either wholly bare of vegetation, or 

 only producing a few grasses and dicotyledonous plants, which constitute true heaths and 

 landes. The moor and bog-lands of Westphalia are remarkable for their flat and table- 

 formed surfaces. From the middle of the Beerktanger Bog, heaven and earth seem to 

 mingle ; no tree, no bush is to be seen far as the eye can reach ; while here and there the 

 play of refraction magnifies to elephants the small and coarse- woolled sheep which find a 

 scanty subsistence on the Erica vulgaris, which vegetates on the scattered productive 

 portions of the bog. The infertile plains, for the most part sandy, occur chiefly in north 

 Germany and Prussia, those of Liineburg and its vicinity occupying a space of about 

 six thousand square miles. Similar sandy plains, interspersed with heaths and marshes, 

 occupy an extensive space in the south of France between the Gironde and the Pyrenees. 

 Towards its eastern extremity, the great level of Europe abounds with enormous tracts of 

 pasture land, which appear to have been rendered smooth by a long abode of the waters 



