286 Dr Hibberts Observations on Vitrified Forts. 



the vitrification of these forts had a volcanic origin ; and hence 

 that volcanoes at some remote period had been very common 

 in Scotland. This opinion was embraced by Mr Pennant, the 

 eminent naturalist, who was led to it from an examination of 

 the Hill of Craig Phasdrick. A similar view was taken up by 

 Thomas West, Esq. the author of a paper published in the 

 Transactions of the Royal Society of London for the year 1777; 

 and, four years afterwards, by the Hon. Dairies Barrington. 



The circumstances which led to this opinion have not been 

 ill explained by Dr James Anderson of Monkshill, Aberdeen- 

 shire, in a letter dated the 27th November 1777, and read to 

 the Antiquarian Society of London " It must be owned," 

 says this author, " that the natural appearance of the places 

 where these vitrified masses are usually found, is well calcula- 

 ted to favour the opinion that they have been produced -by 

 volcanoes. The vitrifiable matter is usually first discovered 

 by travellers around the bottom and on the sides of steep hills, 

 frequently of a conical shape, terminating in a narrow apex, 

 exactly resembling the hills that have been formed by the erup- 

 tions of volcanoes. It is therefore very natural to think that 

 these may have been produced the same way. Let us, for in- 

 stance, suppose that a traveller strongly impressed with this 

 idea, should resolve to examine the top of the mountain more 

 nearly, and for this purpose ascend to the summit : — would 

 not his former conjecture be much confirmed when, at the top, 

 he should find himself in a circular hollow, surrounded on all 

 sides by matter rising gradually higher to the very edge of the 

 precipice, which is there entirely environed with vitrified mat- 

 ter of the same kind with that which he had found at the bot- 

 tom ? Could such a man be called unreasonably credulous if 

 he should be induced by so many concurring circumstances to 

 believe that this had been a real volcano? But would he not 

 be reckoned sceptical in the extreme if he should entertain the 

 smallest doubt of the truth of this opinion, upon seeing the 

 very opening itself in the centre of the hollow, through which 

 the boiling lava had been ejected ?" 



Such is the liberal excuse assigned by Dr Anderson for the 

 volcanic hypothesis, which is the more generous, as he came 

 prepared to advocate a very different theory. Indeed, from 



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