Metalliferous Veins. 161 



had enjoyed such facilities for examining these as I have, he 

 would have remarked that, polished as they are, they are very 

 irregular, and that the depressions are equally bright with the 

 elevations; the striae, too, are seldom parallel, and on opposite 

 sides of a vein they have often reverse dips ; it is by no means 

 unusual to see them curved, contorted, and irregular as a piece 

 of crumpled paper, intersecting each other in all directions. I 

 think it will be allowed that this is not " clear evidence, 1 ' or if 

 so, at all events not in favour of motion. The earthy contents 

 of lodes and cross-courses present the same glittering and striated 

 faces, and with like complications, with still greater frequency. 



Following the idea of intersection being an index of the ages 

 of veins, 'Mr Carne, some years since, attempted a classification 

 of Cornish veins, of which he made eight different ages, older 

 and newer tin lodes ; old, newer, and newest copper lodes ; 

 cross-courses, cross-flucans, and slides : the exceptions given in 

 his instructive publication are, however, as numerous as the 

 cases on which the subdivision is founded. 



The great argument in favour of the mechanical displace- 1 

 ment is supposed to be derived from the accordance of facts, 

 with what would obtain were an elevation of the one side of the 

 traversing vein to take place. This ingenious idea, so far as I 

 am conversant with its history, was first propounded by a Ger- 

 man geologist (the late Herr Schmidt), and was long since sub- 

 mitted to mathematical analysis by Zimmermann, in his publi- 

 cation " Gange, Lager, and Flotze ;"* and lately Mr Hopkins, 

 in his ^ Researches in Physical Geology," has placed it in an 

 English dress. So long ago as 1831, I submitted an outline 

 of it to the Geological Society of London, which, I believe, 

 was little noticed ; I shall again speak of the contents of the 

 paper in which it was inserted. 



It is not easy to explain, unless at great length, by words 

 alone, or even with diagrams, the results of motions on given 

 planes of systems of lines not coincident ; but models of Herr 

 Schmidfs contrivance have been constructed, which beautifully 

 and simply illustrate his theory. We will suppose two lodes 



* The precise title is " Die Wiederausrichtung venvorfener Gange, Lager 

 & Flotze. Von Dr Ch. Zimmermann." 8vo, pp. 204, with six plates. Leipzig, 

 1828. 



VOL. XXII. NO. XLI1I. JANUARY 1837. L 



