Mr Solly on the Motion of Earthquakes. 185 



knew that there had been an earthquake until their arrival at 

 Mendoza. 



These facts are quite in harmony with the theory adopted 

 by Professor Bischof, by Mr Darwin and other eminent geolo- 

 gists, at least partially, which Professor Phillips favours,* and 

 which Mr Lyell requires,t namely, that the nucleus of the 

 earth is an intensely heated liquid or fluid mass. This granted, 

 motion is supposed to be transmitted by subterraneous undu- 

 lations to enormous distances, proportionate to the strength 

 of the explosion, and the depth beneath the earth's surface at 

 which it takes place. Now, we can well imagine that an im- 

 mense mass of mountains, such as the Chilian Andes,+ might 

 ride unshaken (while lower ground sufi'ered) like a ship of the 

 line which moves not with the ripple tossing the little boat at 

 its side. 



Nevertheless we know that the Andes do sometimes suffer 

 extreme dislocations ; for instance, by the Tacna shock of the 

 18th September 1833, of which Mr Matthie Hamilton gives 

 a circumstantial account in your Journal. § He states that 

 after the calamity, when the atmosphere became clear, the 

 Andes, as seen from Tacna, presented a novel spectacle, and 

 in many parts appeared with a new surface, large portions 

 had been thrown off, or had slid into valleys below, leaving 

 some of the more elevated peaks denuded of what had been 

 their more prominent limbs ; and he gives many other similar 

 particulars. Indeed the examples of shattered mountains are 

 too numerous to require citing. 



Mr Darwin expresses his surprise at the effect produced 

 by the Conception earthquake of 1835, on the island of Qui- 

 nquina. He says, " The effect of the vibration on the hard 

 primary slate which composes the foundation of the island 

 was still more curious, the superficial parts of some narrow 

 ridges were as completely shivered as if they had been blasted 

 by gunpowder." II 



* Treatise on Geology, vol. ii. p. 209. 



t Elements of Geology, p. 267. 



t From 11,000 to 23,000 feet high and from 100 to 200 miles across. 



§ Jameson's Philosophical Journal, vol. xxx. p. 153. 



I! Journal of Researches, p. 370. 



