On the Valley of the Jordan and the Dead Sea. 15 



accompanied by the more striking exhibitions, we should ha\re 

 some data by which to measure the amount of change that this 

 force, irregularly active but uniformly modifying in its effects, has 

 wrought upon the configuration of the mountains, their absolute 

 and relative elevation above the bed of the valley, and the 

 changes in the water-courses that flow down them. 



Even then however, we should only arrive at an approximate 

 result of its agency ; since it would be impossible to estimate the 

 relative change of level over so wide a space, especially as there 

 is no well-defined line, like a sea-coast, from which we can de- 

 rive the amount of the movement. 



We are entitled however, to infer from analogous effects else- 

 where observed, accompanied by similar phenomena, that this 

 process of upheaval, with all the changes incident to it, has been 

 going on for centuries in the great region east of Jerusalem ; some- 

 times actively, when the internal fire has made itself visible at the 

 surface, and again slowly during long periods of comparative re- 

 pose, when the disturbing agent has shifted the struggle to other 

 points. We have an example of the elevatory and depressing char- 

 acter of these subterranean movements in the country adjacent to 

 the Caspian, and in the Caspian itself, where the island of Adak, 

 once considerably elevated above the water, has now almost dis- 

 appeared. Among the Caucasian chain great subsidences and 

 upheavals have been noticed to succeed earthquakes. The Med- 

 iterranean has witnessed the appearance of new islands, lifted up 

 from the bottom, violently or gradually, in almost every part of 

 it. The Santorin group has already been mentioned. The isl- 

 and of Merita, near Sicily, arose in 1831, and afterwards disap- 

 peared ; Messina has been the frequent theatre of volcanic action, 

 while the opposite coast of Calabria affords abundant testimony 

 of the modifying and transporting power of volcanic action, in 

 the emergence of new points of land above the surface of the 

 water, the lowering of others, the formation of new lakes in the 

 place of dry land, the elevation of new ridges in some places, and 

 the appearance of wide fissures in others.* 



But Chili and Sweden furnish upon a broad scale the most in- 

 contestable proof of the power of internal heat to elevate vast 

 areas of land. In 1822 the whole coast of ChiH, from the shore 



* Lyell's Geology, Vol. II, pp. 324—352. 



