386 



VOLCANIC ACTION. 



Continuous 

 chain of 

 mountains. 



Elevation 

 of the 

 mountain 

 chains. 



CITAPTER covered during the greater part of summer, being its ter- 



" ' ■ mination. Tlius we may follow the Himalaya system as 



a continuous chain from the Eastern Ocean, through 

 Hindoo-kho, across Candahar and Khorasan, to beyond 

 the Caspian Sea in Azerbijan, along an extent of 73 de- 

 grees, or half the length of the Andes. The western 

 extremity, which is volcanic (like the eastern part), loses 

 its character of a chain in the moimtains of Armenia, 

 which are connected with Sangalou, Bingheul, and Kach- 

 mirdaugh, in the pashalic of Erzeroum. The mean di- 

 rection of the system is north 55° west. 



These mountain chains, with their various ramifica- 

 tions and intervening platforms and valleys, afford evi- 

 dence to our author of revolutions anciently undergone 

 by the crust of the globe ; these having been elevated by 

 matter thrust up in the line of enormous cracks and 

 fissures. The great depression of Central Asia, spoken 

 of above, he considers as having been caused by the same 

 action. Analogous to the Caspian Sea and other cavities 

 in this district, are the lakes formed in Europe at the foot 

 of the Alps, and which also owe their origin to a sinking 

 of the ground. It is chiefly in the extent of this depres- 

 sion of Central Asia, and consequently in the space where 

 the resistance was least, that we find traces of volcanic 

 actions. 



On this subject of volcanic action, and the upheaval 

 and depression of vast areas, much new and very impor- 

 tant light has recently been brought to bear from an 

 entirely novel source. Turning from the phenomena of 

 our own planet, philosophers have directed their improved 

 telescopes to the moon, and by an intelligent analj'ses of 

 the peculiar features which it exhibits have been able 

 largely to add to our knowledge of the sources of many 

 of the most remarkal)]e physical characteristics of our 

 own planet. At the meeting of the British Association, 

 held at Edinlnu'gh in 1850, Mr Nasmyth made a most 

 interesting communication on the lunar surface. His 

 attention, he said, had been directed for some time to 



Volcanic 

 action. 



