320 THEORIES OF ORE DISPOSITION HISTORICALLY CONSIDERED. 



perhaps the first to Avhom doubts came as to the correctness of his 

 master's teachings, while studying an eruption of Vesuvius in 1799, 

 though he refrained from immediate publication of these doubts. 



D'Aubuisson, the French geologist, after visiting, in 1804, the vol- 

 canic regions of Auvergne, also became convinced of its igneous origin 

 and published a recantation of the views maintained in his essay of 

 the previous year on the aqueous origin of the basalts of Saxony. 

 Finally, von Humboldt (1810), perhaps the greatest of his pupils, 

 in his extended observations in the Cordilleran system of the Amer- 

 ican continents, traced a direct connection between metallic deposits 

 and the eruptive rocks. 



Observation must have convinced many of Werner's pupils of the 

 untenability of his peculiar views on the formation and filling of 

 veins long before their final refutation was published by his succes- 

 sor, von Beust, in 1840, but reverence for his memory doubtless pre- 

 vented a definite expression of their opinions in print. 



Von Herder, in his work on the Meissner adit, published in 183S, 

 classified the various theories on the origin of veins that had been 

 held up to that time, as follows: 



1. Theory of contemporaneous formation (with the inclosing rock). 



2. Theory of (filling by) lateral secretion, or by material derived 

 from tlie inclosing rocks. 



3. Theor}^ of (filling by) descension, or filling from above. 



4. Theory of (filling by) ascension, or filling from beloW', the lat- 

 ter subdivided into : 



(a) B}^ infiltration, or solutions from mineral (thermal) waters. 



(b) By sublimation, or by ascending steam. 



(c) By sublimation, or in gaseous condition. 

 (r/) By injection or in igneous fluid state. 



He was thus apparently the first to apply the now time-honored 

 terms " ascension," " descension,'" and " lateral secretion,'' though the 

 idea was clearly expressed thirty years before by Cuvier's collab- 

 orator, Alexandre Brogniart, when, in an attempt to reconcile tlie 

 Huttonian and Wernerian schools, he showed that no one theory 

 could fit all kinds of v'eins. 



Tlie theories of contemporaneous formation and of descension had 

 by this time become j)ractically obsolete among the Germans, and 

 had never had much standing among geologists of other nations. 

 German geologists, who have been the most assiduous students of 

 vein phenomena in the field, have always been inclined to assume 

 that vein minerals have been deposited by precipitation from a(|ue- 

 ous solution, differences of opinion having been mainly as to the 

 provenance of the waters. Doubtless the influence of Werner had 

 much to do with their mental attitude, but it is also to be remarked 



