34 THE ORIGIN OF MOUNTAINS. 



of the railway carriage to catch a glimpse of their summits. And 

 I was equally impressed with the panorama of mountains seen 

 from Keswick, which exceeded in grandeur all the notions I had 

 gathered from books and pictures. 



Much might be said about the uses of mountains. Their influence 

 on climate is well known. We are aware how we can pass from 

 tropical to arctic regions as well in ascending the Himalayas as in 

 going from their base towards the poles. 



And it is a very interesting question to compare the plants and 

 animals distributed over the superficial /ones with those occurring 

 in zones of altitude, and to trace out the various influences which 

 have led to their present distribution, when under existing con- 

 ditions no means of migration may exist. 



The temperature decreases 1° for about every 350ft. in elevation, 

 for the atmosphere less dense is less capable of retaining heat. It is 

 wanned chiefly by the earth, the lower strata of the atmosphere being 

 heated by direct contact with the earth, the higher only by radiation. 

 Moreover, " as the air expands under the diminution of pressure in 

 the higher regions, it absorbs sensible heat to maintain the expansion 

 of its own substance, and renders that latent and insensible. The air 

 itself thus becomes cold, in consequence of its warmth being taken 

 away from it for us.' in a different way." * 



The snow line in tropical regions varies from 15,000 to 20,000 feet 

 above the sea. Mountains are great condensers, hence the great 

 rainfall in hilly regiuns. In the Khasia Hills, behind the Bay of 

 1, hot moist winds from the Indian Ocean create an annual 

 rainfall of 50ft. ; it is the rainiest district in the world. In the 

 Lake District we have in some parts an annual fall of from 15ft. to 

 1 Hft ., while a\va\ from the mountains it sinks even on the same coast 

 to sometimes only 2Jft. 



Mr. Grove observes that "We in Europe can form little idea of 

 v. ii.it a frightful calamity the want of mountains and streams is. 

 Australia will probably Buffer from it to the end of time. Had that 

 great continent been divided by a range of mountains, sufficiently 

 loft] to have had perpetual snow, and thus to intercept the hot winds 

 and rob them of their moisture, it would have been one of t^.e richest 

 countries m the world ; and its interior, instead of being, as much of it 

 Lb, a wilderness of countless Band ridges, itself devoured by scorching 

 winds, and the source of drought and oppression to the settlements on 

 ^t, would have been one giant field of oorn and pasture." 



Ee remarks also that " mountains have played a ^reat part in the 



history of many countries by affording a refuge for the i pie when 



the lowlands were conquered, and preserving for lon^ the names, 

 manners, and customs of the first inhabitants of the country, 

 far away from cities and communication with the rest of 

 the World, they preserve the simple virtues of primeval life, though 

 they also preserve its ignorance and prejudice." 



• B, J. Mann, in " Modern Meteorology," 1879, p. 28, 



