iv Hutton and Werner compared 177 



series of veins, but regarded them all as due to the intro- 

 duction of igneous material. Though more logical than 

 Werner, he was, as we now know, entirely in error in 

 confounding under one denomination two totally distinct 

 assemblages of mineral matter. Werner correctly referred 

 veins of ores and spars to deposition from aqueous solution, 

 but was completely mistaken in attributing the same 

 origin to veins of massive rock. Hutton, on the other 

 hand, went as far astray in regard to his explanation of 

 mineral veins, but he made an important contribution to 

 science in his insistence upon the truly intrusive nature of 

 veins of granite and whinstone. 



There was another point of difference between the 

 views of Werner and of Hutton in regard to mineral 

 veins. One of the undoubted services of the Freiberg 

 professor was his clear demonstration that veins could be 

 classified according to their directions, that this arrange- 

 ment often sufficed to separate them also according to 

 age and material, those running along one parallel, and 

 containing one group of minerals, being intersected by, 

 and therefore older than, another series following a different 

 direction, and consisting of other metals and vein-stones. 

 This important distinction found no place in Hutton's 

 system. To him it was enough that he was able to show 

 that the veins known to him were intrusive masses of 

 igneous origin. 1 



In the Huttonian theory we find the germ of the 



1 In Playfair's Illustrations, however, the successive origin of mineral 

 veins is distinctly affirmed, 226. Reference is there made to the coin- 

 cidence between the prevalent direction of the principal Cornish veins and 

 the general strike of the strata, and to the intersection of these by the 

 cross-courses at nearly right angles. 



N 



