Memoir on the Geology of the Environs of Lons- 

 le-Saunier. By M. Charbaut, Engineer 

 cfthe Mines. 



Read to the Society of Emulation of the Jura, December I, 1818. 

 (Annates des Mines for 1819.) 



The Jura mountains afford the finest field possible for 

 geological observations ; yet, it must be confessed, that not 

 only is their structure unknown, but, what is infinitely more 

 vexatious, that prejudices and errors, sanctioned by natu- 

 ralists otherwise justly celebrated, mislead the geologist who 

 takes them for guides, cause him to commit new errors, or 

 discourage him by their frequent opposition to the facts 

 which offer themselves to his contemplation. 



The darkness that yet covers the geological history of 

 such an interesting country, is principally owing to the man- 

 ner in which, until now, this science has been studied ; but 

 it may be hoped that it will be dissipated, since one of the 

 best works that does honour to French naturalists, has given 

 to geology a new direction and range. 



When the texture, the facies of rocks, and their chemical 

 composition were the only distinctive characters of forma- 

 tions, the primitive rocks offered infinitely more facility for 

 study than the secondary series ; I conceive I am not the 

 only person who has remarked that if we had excellent 

 precepts for the former, geologists had taught us nothing 

 satisfactory concerning the latter. 



