VALLEYS AND OREAT LEVELS OF THE EARTH. 



221 



surface ; for while in the former the difference between high and low is that of thousands 

 of feet in a very small space, in the latter frequently it does not amount to fifty feet, nor 

 in some cases to ten, through a wide area, but the surface rises and falls in gentle wavy 

 lines, which offer no relief to the dull uniformity of the scene. The surface of these 

 levels is usually composed of the most recent aqueous deposits, the loosely deposited beds 

 of clay, sand, and rolled pebbles, characteristic of newly elevated land. They may be 

 classed under the general denomination of plains, but the term will then have great 

 latitude of meaning, and include regions of very diverse aspect and character. Giving it 

 a wide acceptation, not only will low flat districts rank as plains, but tracts of horizontal 

 land at an immense elevation above the sea, and extensive districts which are traversed 

 by valleys, ravines, and hills, but exhibit in contrast with mountainous countries a 

 generally level surface. 



The great levels of the earth vary as to their elevation above the sea from a few feet 

 to between two and three miles, while some are actually depressed beneath it. 



Feet above 

 the Ocean. 



200 to 250 



Feet above 

 the Ocean. 



Switzerland between the Alps and 



the Jura - 

 Steppes of the Kirghis 

 Plains of Bavaria - 

 Plains of the two Castiles - 

 Mysore - - - - - 

 Plains of Persia - 

 Plain of Quito 

 Plain of Titicaca 



1400 



1300 to 1600 

 1650 



1800 to 2000 

 2300 to 2600 

 3800 to 4200 

 9000 

 13,000. 



The Plains of Hungary are from 



Plains from the Scheldt to the Ye- 

 nisei, extending through 80 of 



longitude - ... 250 to 300 



Plains of Moscow ... 460 



Plains of Lombardy - - - 500 



Plains of Lithuania "-'. - - 600 



Suabia - ..-,-, " " ^ 



Plateau of Valdai *~ -_ - 1000 



Auvergne 1100 



To the more elevated plains, the terms plateau and table-land are applied, which 

 Humboldt proposes to confine to elevations producing a sensible diminution of 

 temperature, or to heights which attain to 1800 or 2000 feet, and upwards. Some writers, 

 however, draw a distinction between plateau and table-land which seems appropriate. 

 According to this distinction, a plateau is a great extent of country raised above the 

 general surface, upon which there may be systems of mountains and valleys insterspersed 

 with plains, while true table-land, on the contrary, consists simply of an extensive 

 elevated region, which abruptly ascends from the neighbouring country, with a level or 

 gently undulating surface. 



The grandest example of plateau upon the face of the globe is in Central Asia. It 

 consists of the region of Chinese Tartary and Thibet, an immense tract of country very 

 imperfectly known, but at a mean height of many thousand feet above the sea. It is 

 supported by immense ramparts of mountains, the summits of which rise far above the 

 elevated interior. In the following section of the continent from the Black Sea to the 



Pacific Ocean, this great 

 plateau appears bounded 

 on the west by the heights 

 of Belur-tagh, or the 

 Cloudy Mountains, and 

 on the east by the Yung-ling range, which divides China from Thibet by a series of 

 snowy peaks. Fig. 1. represents the level of the Black Sea; 2. the height of Mount 

 Ararat ; 3. the level of the Caspian ; 4. Tartary ; 5. the Belur-tagh, or Cloudy Moun- 

 tains ; 6. the plateau of Crim Tartary; 7. the mountains of Yung-ling ; 8. China; and 

 9. the Pacific Ocean. 



The next is a section of the continent from the Arctic to the Indian Oceans, which 

 shows the Altaian Mountains, the boundary of the plateau to the north, and the Hima- 



