On the Basaltes of Saxony. \ QQ 



fbcks produced in the humid way* The calc^retiu's and 

 schistous rocks, &c. are every where similar; while the 

 lava of Solfaterra, Lipari* and Vesuvius., are sensibly dif- 

 ferent, notwithstanding their proximity to each other. Nay, 

 more, the lava thrown, up by the same volcano is far froiii 

 being identic : and how can the case be otherwise, since 

 the foci of these volcanoes, placed in the middle of different 

 rocks, must impress on the substances thrown up charac- 

 ters as various as the matters which are subjected to their 

 action ? 



These considerations would be of little weight in the hy- 

 pothesis of Dolomieu. The lava of the author of this me- 

 moir would belong to the strata which compose the crust of 

 the globe : the basaltes would have issued from the greatest 

 depths, from that common reservoir where this great ob- 

 server of Volcanoes sought for the origin of the greater part 

 of his lithoid lavas. But could basaltes ever be fused ? This 

 C. Daubuisson denies, and it is from the crystals contained 

 in it that he thinks he can deduce his most decisive proofs. 



The crystals and grains found in basaltes are generally 

 amphibolite, olivin, pyroxene, and feldspar, &cc. These 

 either must have pre-existed in the basaltes, and they must 

 have been enveloped by the matter in fusion, or must have 

 been formed in the bosom of that matter by the aggregation 

 of the molecular of the same nature found disseminated in 

 it. In the first case, how could those which are more fusi- 

 ble resist the heat which reduced them to the fluid state ; 

 and how could those which are more refractory preserve 

 their colour, their transparency, and their splendour ? In 

 the second case, would not the paste-like fluidity of this 

 lava have yielded to the movements of these moleculae, and 

 would not the heat have imprinted its character on their ag- 

 gregation ? But these crystals and grains which are gene- 

 rally found in basaltes are not the only bodies inclosed in 

 them. The author found also gres. Others speak of se- 

 veral other substances, and particularly calcareous frag- 

 ments. According to Werner, the basaltes of Carlsbad, in 

 Bohemia, contains so large a quantity of it that it is em- 

 ployed for making lime ; and Saussurc relates in his Travels, 

 that he saw basaltes which contained angular fragments of 

 compact gray calcareous stone, which was in no manner 

 altered at the point of contact. Nav, fossils themselves are 

 not entirely foreign to this rock, and to that of the same 

 epoch. M. de Buch found turbinites in a rock of trap. 

 The author quotes Dr. Blagden and Mr. Chenevix as hav- 

 ing seen the impression of shells in the hardest and most 



. compact 



