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HUTTONIAN THEORY. 



379 



Of this 



arud of th€ fame elevation with itfelf. 

 rock no part remains. 

 The bafaltic rock of Edinburgh Caftle is near- 



■ L 



ly in the fame ftate. Its perpendicular fides on 

 the fouth, weft, and north, are now difengaged 

 from the flrata by which they were once en> 

 compaffed. 



340. The granite mountains alfo, where they 

 are quite unftratified, give rife to the 



to the fame co 

 Thofe central chains which we find 

 fo many inftances towering above the fchift 



clufi 



s 



which cover th 



fid 



have p.robably bee 



completely enveloped by the latter ^ and 



this fuppofi 



an 



ftimate may fomedmes be 



formed of the original height of fuch mountains 



I 



thefe 



11 



however, fome uncer- 



tainty muft arife, from our being unable to di- 

 ftinguilh between the effe6ts which are to be 

 afcribed to the fradure and diflocation that 

 took place when the compound body of flirati- 

 fied and unftratified rocks was raifed up from 

 the bottom of the fea, and the effeds produced 

 by the fubfequent wafte and decompofition at the 

 furface.- In this, as in many other inftances, 

 we are not always able to feparate between the 

 original inequalities of the furface, and thofc 



which wearing has pruduced. 



341. It would be important to afcertain the rate 

 at which the elevation of mountains decreafes, and 



this 



