LIFE HISTORY OF A MOUNTAIN 



247 



Frost, sun, rain, over, glacier, sea and masses of granite may be shattered into 

 wind are the prmcipal agents of destruc- fragments and lie about, a picture of 

 tion. ruinous decav 



A mason in sculpturing a block of stone 

 "begins b\' chipping away 



The agents engaged in finishing the 



flake after flake until the 

 desired shape is roughly at- 

 tained. Then he uses finer 

 tools to produce more de- 

 tailed outlines, and the final 

 effects are secured by polish- 

 ing. 



So in rock sculpture — frost 

 and sun do the roughing 

 out, and the other agents 

 principall}^ act as finishing 

 tools. 



The effects of frost are 

 mostly felt in high latitudes 

 and at great altitudes. We 

 know from personal experi- 

 ence the effects of water 

 freezing in our domestic 

 supply pipes. We may not 

 discover that the pipe has 

 been broken until the thaw 

 comes and the water floods 

 our dwellings. In the same 

 way. the water contained in 

 the cre^•ices of rocks expands 

 on freezing, with almost irre- 

 sistible force, and shatters 

 even the hardest material 

 into fragments ; the flakes 

 are held fast until the spring 

 comes, and then the debris 

 rains down to form a talus 

 of stones at the base of the 

 slope. We see the work of 

 frost -flaking in the granite 

 pinnacles or aiguilles of the 

 high Alps, the mountains of 

 Corsica.* and in all compact 

 rocks subject to great cold. 



In our latitudes it is hard 

 to realise what sun-flaking 

 means, but standing under 



the tropical sun, and face to face with work roughed out by frost and sun are 

 the riven rocks, it becomes very real, more influenced by the texture of the 



LEAVING THE FKAMEWOKK OF llAKDEK KOCKS STANDING 

 LIKE A BONY SKELETON STRIPPED OK ITS COVERING 

 FLESH." 



During the day the stones become in- 

 tensely heated and expand ; at night, 

 when the sun's rays are withdrawn, they 

 rapidly chill and contract. Thus by 

 alternate expansion and contraction even 



* See also tlie coloured plate of Mr. MarWhirter's 

 picture, "June in the Austrian Tyrol," in Part 3. 



material on which they oi)erate. The 

 softer parts rapidly decay, leaving the 

 framework of harder rocks standing like 

 a bony skeleton strii)ped of its covering 

 flesh. Moving water, ice and air can 

 do little of themselves. It is the harder 

 material they carry in suspension which 



