148 Analyses of Booh. [Aug. 



and the stream of lava, 200 feet broad, is observed, after having 

 flowed for some way, to divide into two, the smaller currents then 

 making their way to the low grounds in different directions, to the 

 distance of four or five miies. These lava streams receive the 

 general denomination of chcires from the inhabitants of the coun- 

 try. They commonly form a most barren and ungrateful soil : the 

 cheire that proceeds from the Puy de Come is so remarkable for its 

 sterility that it is called cheire de I'aumone. 



The surface of the lava is generally blistered and extremely 

 rough, some of the asperities projecting several feet. An idea of 

 the roughness of its surface may be formed, by supposing it to 

 resemble that of melted lead poured into water. The interior of 

 the lava is of a greyish black colour, of a fine compact grain, hard, 

 brittle, and frangible, differing from common basalt in these last 

 characters. It contains crystals of augite and of felspar, the latter 

 having a vitreous aspect, and rarely grains of olivine. The lava of 

 the Puy de la Vache, however, very much resembles common 

 basalt. It is vesicular at the surface, but fine-grained or compact 

 in the interior or at the bottom. 



The cheire of Volvic is in some respects an exception. Its sub- 

 stance is of a Uglier colour, and so soft that it is easily worked. 

 Quarries have therefore been opened in it, and it affords a pretty 

 good building material. It contains pieces of quartz altered by the 

 heat; and the walls of the cavities which occur in it are set with 

 spangles of specular iron ore. This cheire of Volvic had evidently 

 flowefl from the Pny of Nugcre. A spectator standing on the 

 summit of this hill has a distinct view of the stream of lava which 

 had issued from the crater beside him. He perceives that, in 

 descending to the low ground, it had spread over a large basin, 

 bounded by rocks of granite, and had surrounded some detached 

 locks which interrupted its progress. The tops of these detached 

 granite rocks are seen rising above the surface of this lake of lava. 



" When I thus perceived (says Mr. JDaubuisson) that these lava 

 streams had avoided obstacles, and obeyed all the laws of hydrody- 

 namics, I could not help reflecting, that if the infringement of 

 these laws by the basalts of Saxony had formerly influenced my 

 opinion against admitting their igneous formation, the exact obeying 

 of the same laws in this case ought to produce an opposite convic- 

 tion in regard to those of ^iwergne." 



It appears therefore, as already mentioned, that if Mr. Dau- 

 buisson was formerly inclined, from analogy, to consider all basalts 

 as of aqueous origin, he has in so far altered his views, that he now 

 excepts those of shiver gne. This seems to be the extent of any 

 change of sentiment ; and it is without reason that some incautious 

 writers have suited, that Mr. Daubuisson has entirely altered his 

 opinion concerning the origin of basalt in general. His opinion, 

 stated in the most favourable way for the volcanists, may be sup- 

 posed to amount to this, that a substance nearly identical in cha- 

 racter and nature may have been produced either from fusion or 



