Dr. Mac Culloch on Mineral Veins. 185 



veins : but, as no useful information is coramunicated by the 

 adoption of provincial and technical terms, they are here avoid- 

 ed. Geology can gain nothing by being further encumbered 

 with terms that only produce an unnecessary jargon ; and it is 

 the duty of every one to avoid sullying the English tongue. To 

 shroud in the mystic terms of any science or art, whether in 

 the phraseology of miners or the symbols of algebra, that which 

 can be expressed in ordinary language, is either the result of a 

 worthless ambition, or a proof of the superiority of the memory 

 to the understanding. 



Of the Forms, Positions, and Relations of Mineral Veins. 



Blineral veins, like rock veins, intersect the strata at all 

 angles, and are also occasionally parallel to them, throughout 

 more or less of their courses. They imply a discontinuity of 

 the rocks through which they pass, and are, in fact, composed 

 of matter which has entered into the fissures that have been 

 formed by the causes which influence the positions of strata. 

 Hence, it is easy to understand how they are accompanied by 

 those dislocations of the including strata, the varieties of which 

 are numerous ; although a fissure does not necessarily imply a 

 dislocation. 



As veins tnay hold any direction with regard to the including 

 strata, so they may be placed in any position towards the 

 horizon. But from a mere comparison of chances, it is plain 

 that they must be far more frequently inclined than vertical ; 

 whence miners learn to distinguish between the upper and 

 under sides of a vein. It is observed, that when mineral veins 

 occur in considerable numbers in any tract of country, they 

 maintain a sort of general parallelism ; as if all the fissures to 

 which they owe their origin had been formed, at the same time, 

 by some common cause, or had been produced by the succes- 

 sive repetition of similar actions. This, also, it is remarkable, 

 is sometimes the case where more than one set of veins exists, 

 and where the posteriority of the one is proved by their inva- 

 riably intersecting the other. This fact is remarkable in Corn- 

 wall, where the more ancient veins are directed, in a general 



