472 BevieiDS — Prof. Daubree's Stratified Bocks. 



Des Terrains Stratifies, consideres atj Point de Vue de 

 l'Origine des Substances qui les Constituent et du Tribut 

 que leur ont apporte les parties internes du guobb. 

 By M. Daubree. (From the Bull, of the Geol. Soc. of France, 

 2nd Series, vol. xxviii. p. 363. Paris, 1871. pp. 58.) 



THIS "note" as it is called is in truth an elaborate essay on that 

 most intricate of subjects — the chemical origin of rocks. It 

 abounds in references to previous works on the subject, although 

 some writers who are identified with it, such as Dr. Sterry Hunt for 

 instance, are curiously enough absent from the list of those quoted. 



In studying the origin of the composition of the sedimentary 

 rocks as we know them now, M. Daubree is not content with 

 tracing their constituent parts to the more recent reservoirs of 

 sea and land, whence they were undoubtedly in the last instance 

 derived, but, like an enthusiastic pedigree-maker, he must fain go 

 back to the dark ages, and the interior of the earth is the great 

 laboratory to which he pushes back all or almost all our familiar 

 rock-making substances. Of course much of what M. Daubree 

 advances is pure hypothesis, and the " scientific Uses of the Imagi- 

 nation" are nowhere better shown than in disquisitions dealing 

 with such obscure and unknown regions as the "Bowels of the 

 Earth." The paper is, however, full of suggestive thoughts, and is 

 useful as giving in a clear and definite manner the opinions of a 

 chemist and geologist so well known as is its writer. 



M. Daubree unites with M. Delesse in attaching considerable import- 

 ance to the submarine volcanic deposits of which, beyond the fact of 

 their existence, we really know very little. To them, including 

 of course thermal waters charged with all kinds of extraneous sub- 

 stances, the presence of most of the rock-forming bodies not directly 

 attributable to trituration is referred by them. To the sea with 

 its many constituents M. Daubree does not allow much influence in 

 the formation of great deposits unless it be aided by subterranean 

 heat. With regard to rock-salt, for instance, he says, that although 

 the theory that it could be produced similarly to the salt which is 

 found in the neighbourhood of volcanoes is untenable,^ yet the mere 

 evaporation of salt water at the ordinary temperature cannot satis- 

 factorily explain its existence, since it would not account for the 

 preservation of deliquescent salts, such as carnallite. "How," he 

 adds, " without mentioning Borate of Magnesia or Stassfurtite, could 

 Hematite, limpid quartz with very distinct forms. Anhydrite in com- 

 plete crystals, such as are scarcely known elsewhere, and Boracite such 

 as has quite recently been found there, have crystallized in the midst 

 of these deposits?" These facts amongst others convince our author 

 that the evaporation to which deposits of rock-salt " apparently " 

 owe their origin was caused, not by the action of the atmosphere 



1 This theory was held by Breislack, de Charpentier, Paul Savi, and others. 



