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f6me light is often to be had, even in this difficult queffion/ 
and merely from the phyhcal geography of the country, 
independent of the particular ftrudlureof the hills them- 
felves. For countries have their external charadlers, ac- 
cording to the nature of the hills that compofe them ; 
though thefe chara6lers feldom form a part of the geo- 
grapher’s inquiries; geography having never yet been 
formally conhdered, but as fubfervient to civil hiftory. 
Iffiall not enter particularly into thisqueffion at prefent; 
only ffiall obferve, that the difference, in the external 
characters of mountains, according to their internal ftruc- 
ture, is eaiily feen, on comparing, for inffance, the out- 
ward forms of mountains of granite, or other limilar vi- 
trifiable compound ftones, which are of an irregular 
ftruCture, with thofe of limeftone, which are commonly 
formed in regular Jlrata. Signal examples of this are 
obfervable in the chain of mount Jura, which is exclu- 
fively calcareous, and of a horizontal fummit, and that of 
the Alps, whofe higheft mountains are mol lly of granite, 
and terminate in pics, pyramids, and other irregularly 
pointed forms, according to the nature of fuch moun- 
tains. When therefore a remarkable limilitude is ob- 
fervable, between the forms and difpofition of the hills 
and vallies of a vulcanic diftriCt, and thofe of other coun- 
tries of a certain character, that have not buffered by fire, 
it is reafonable enough, upon th e principles before adopt- 
ed, to fuppofe the fame limilitude even in the primary 
ftruCture and qualities of the former, however thCy may 
have been obliterated by the intervention of fire. The 
vulcanic 
