Crystalline Limestone, 35^. 



that the crystal-forming agents produced the result which we 

 have before us, after the deposition of the formation at the 

 bottom of the sea. Should it even be necessary to assume, 

 that solution did not take place at all during the process, and 

 that these agents have had to work in a perfectly solid mate- 

 rial, we can easily recall to our remembrance some facts 

 which, notwithstanding an old chemical doctrine, render it 

 incontrovertible, that a substance can crystallize without hav- 

 ing previously been in a liquid state. Inasmuch as it is only 

 from geognostical considerations that our attention is direct- 

 ed to these facts, which hitherto have not been applied in 

 geology (probably, because they were placed in the shade 

 by the axiom alluded to), we perceive that, in such a way 

 also, these considerations are not vrithout their fruits. From 

 the study of the subject, in this point of view, the follow- 

 ing events in the history of the Wenlock formation present 

 themselves, and these, though perhaps not so well established 

 as the experimental chemist requires, must, nevertheless, be 

 regarded as certain, viz. : The deposition of masses of mud 

 containing clay and lime, and of other mechanical products, in 

 which the marine organisms of the period became enveloped ; 

 the concentration and crystallization at certain places of the 

 carbonate of lime, from which the clay was then removed ; the 

 bringing together, and crystallization of the silica and carbon, 

 for the formation of rock-crystal and leaflets of anthracite in 

 the nodules in which these minerals are found ; all by pro- 

 cesses slowly operating at the usual temperature. To these 

 may be further added the production of the veins by means 

 of similar slow movements of the substances in the hardened 

 masses. 



It is no small proof of the irresistible power with which the 

 matter-of-fact circumstances of the case speak to the observer, 

 that these very circumstances have called forth such ideas as 

 those already stated, from a geologist, who is one of the most 

 faithful in following the rule, that the theoretical geologist 

 must, at all times, unconditionally place himself under the au- 

 thority of chemistry. Murchison, who is a keen volcanist, 

 does not, however, venture in the case of the Wenlock forma- 

 tion, to call in the aid of any *' subterranean agency ;"* although, 



