344 



ELEVATION OP CENTRAL ASIA. 



mountains are the most recent." — From the imperfect knowledge at 

 present possessed of the geology of central Asia, and of the structure 

 of the mountains, it would be unwise to draw any general conclusions 

 respecting the elevation of the different mountain chains, or of the 

 elevated plateau from which they rise ; but we can scarcely con- 

 ceive, that the whole of the mountain chains, and this elevated plain 

 in central Asia, were raised by one sudden upheaving force : it seems 

 more probable, that the expansion of so large a portion of the earth's 

 surface, and its depression in other parts, w^ere not effected in a very 

 short period ; but still the convulsive intermissions of such an up- 

 heaving, while in progress, must have produced tremendous effects. 

 If this elevation of central Asia took place after the tertiary epoch, 

 perhaps it may not have an earlier date than the existence of the hu- 

 man race, and its destructive effects on the surrounding countries, 

 may have given rise to the tradition of an extensive deluge, still pre- 

 served among the most ancient eastern nations, and referred to in the 

 writings of Moses. 



The elevations of limited portions of the earth's surface, at a dis- 

 tance from any known volcanic agency, are not uncommon. Loose 

 ! stones or shingles of an ancient sea beach, are found at heights con- 

 siderably above the present level of the sea, in many parts of Eng- 

 land. Beds of gravel and diluvial sand, with marine shells, were re- 

 cently found on the summit of Moel Tryfane, near Caernarvon, at 

 the height of 1000 feet above the level of the sea : the shells are 

 said to resemble the broken shells on the adjacent beach. On the 

 coast of Norway and Sweden, Von Buch and M. Brongniart discov- 

 ered deposits of shells at various heights above the level of the sea ; 

 this would indicate that the rocks have been elevated at a recent pe- 

 riod, though they are chiefly composed of gneiss and primary forma- 

 tions. In countries that are adjacent to volcanic districts, instances 

 of the repeated elevation and submersion of the land are not uncom- 

 mon. In the first volume of Mr. Lyell's Principles of Geology, ma- 

 ny interesting facts of this kind, in Calabria and Sicily are fully sta- 

 ted. The most remarkable elevation of the ground that has been 

 recorded in modern times, is that which took place, in the year 1822 

 (see Chap. V.,) on the coast of Valparaiso, in which the bed of the 

 sea was raised permanently above its surface, over an extent of 100 

 miles. 



It may be truly said that these instances of elevation, present but 

 a feeble resemblance to the mighty upheaving forces which have ele- 

 vated whole continents ; but I before stated, that it is highly proba- 

 ble the emersion of continents from the ocean, was a slow and long 

 continued process. We have fevs^er recent instances of subsidence 

 on an extensive scale than of elevation ; though cities have been in- 

 gulfed and their place occupied by lakes, and the bed of the sea 

 near the coast, has been deepened as well as elevated by earth- 

 quakes. In addition to this, there are submarine forests on some 



