148 GLACIER FORMATION. 



situations, the heat of the sun serves only to 

 melt the snow upon the more exposed parts 

 of mountain summits and elevated plains, caus- 

 ing streams of water which, in their descent, 

 percolate the snow beneath and enter a region 

 of perpetual frost, where the whole mass speedily 

 becomes converted into an icy substance, more 

 or less opaque, according to the suddenness and 

 profuseness of the thaw of the exposed parts. 



Insignificant as the streams occasioned by so 

 partial a thaw may be thought, yet, when it 

 is considered that they are of almost daily oc- 

 currence from June to October, it is evident 

 that a large accumulation of ice must annually 

 take place ; which, being repeated year after 

 year, and counteracted only in the early stage 

 of the berg by a trifling diminution of its sur- 

 face from the effect of the summer temperature, 

 it is clear that in the course of time a body 

 may arrive at such a magnitude that its further 

 increase will be prevented only by the breaking 

 away of its own overgrown dimensions. 



Whilst upon this curious subject, it may be in- 

 teresting to see how far the opinions above-men- 

 tioned, formed on the spot, and recorded many 

 years ago, are borne out by the recent observa- 

 tions of travellers who have had opportunities of 

 minutely examining the glaciers in the southern 



