Beds and Veins, 21 



we admit actual movements or displacements of a portion of 

 the mountain-mass at a bounding-surface, whether that be a 

 mere distinct-concretion-surface, a rent, or even a distinct vein, 

 although appearances may be favourable to a belief in such a 

 shift. 



It is evident from the above, that mountain-masses of in- 

 considerable dimensions, which, generally speaking, lie con- 

 formably to the structure of the slaty rocks, and hence are 

 considered as bed-like, and are termed heds^ yet neverthe- 

 less cut this structure here and there, sometimes for shorter, 

 sometimes for longer distances ; sometimes under greater, 

 sometimes under smaller angles. When the places, in a 

 series "of beds, where this occm's, are several, and the cut- 

 ting angles are greater than those at which the mass lies 

 conformably to the beds, it assumes a vein-like character, and, 

 in one w^ord, becomes a vein. Vice versa, a vein is defined to 

 be a bed- (/, e. table-) shaped mass, which cuts the structure 

 of the mountain-masses of slaty rocks, for, in others than the 

 slaty rocks, the cutting through cannot be observed. But 

 there are many otherwise extremely characteristic veins, which 

 partly do not do this ; and even some which, throughout their 

 whole extent, lie generally conformably to the slaty structure. 

 Under these circumstances, it is difficult, when the beds and 

 veins contain merely rocks like granite, porphyry, greenstone, 

 basalt, &c. to assign the limits between the bed and vein ; and, 

 without entirely throwing away the distinction, the conse- 

 quence has been drawn, and it is a useful one, even for the 

 present investigation, that we ought not to attribute too much 

 importance to this distinction. In regard to the beds and 

 veins which have hitherto been considered, this is of less con- 

 sequence. It may serve, how^ever, to direct attention to the 

 essential difference between beds and veins of ore ; and, should 

 it thence perhaps appear that it likewise is not so great as it 

 is generally assumed to be, this may certainly acquire some 

 influence on the procedure which is to be followed in search- 

 ing for such repositories. 



( To be continued in oar next number,) 



