HUTTONIAN TPIEORY. 



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country lies on the eaft fide of the Plata, and is 

 a f'plain, extremely level, and of vail extent, 

 without any appearance of mineral veins ; but 

 fuch veins may neverthelefs exiil undifcovered, 

 in a trad fabjecl to periodical inundations, and 

 where the native rock is covered with alluvial 

 earth and gravel to a great depth. The veins may 

 be wafhed away, and the more durable fubflan- 

 ces, fuch as thofe pieces of native iron, may be 



left behind ; and, though they mail be of a for- 



mation extremely ancient, according to this hy- 

 pothefis, they may not have been very long on 

 the furface. 



213. Specimens of native iron have been 

 found, lefs remarkable than the preceding for 

 their fize, but in circumftances that excluded 

 all idea of artificial fufion. Of this fort was 

 Margraaf's fpecimen of native iron, the firft of 

 the kind that was known ; it confifted of fmali 

 bits of foft and malleable iron, found in the 

 heart of a brown iron-ilone*. This makes it 

 certain, that native iron is a natural production, 

 and the mere circuniftance of great magnitude, 

 in the fpecimens before mentioned, does not en- 

 title us to doubt of their having that f;UTie ori- 



It is a circuniftance, befides, not in the 



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* Kir^van's MineralogYj vol. ii. p. 156. 



