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Show 346 RELATIVE ANTIQUITY [Ch,XXIV. dinavia, certain chains in Morocco, and the littoral Cordillera of Brazil, were formed! Not only do these speculations refer to mountains never touched, as M. Bouc remarks, by the hammer of the geologist, but they proceed on the supposition, that in these distant chains the geological and geographical axes always coincide. Now we know that in Europe the strike* of the beds is not always parallel to the direction of the chain. As an exception, we may instance that pointed out by Von Dechen 1-, who states that in the Hartz the direction or sl·rike of the strata of slate and grey. wacke is sometimes from E. and W. and frequently N. E. and S. W.; whereas the geographical direction of the mountainchain is decidedly from E. S. E. toW. N. W. In addition to these uncertainties, which should, in the present state of science, have deterred a geologist even from speculating on the phenomena of unexplort!d regions, the im. portant admission is made by M. de Beaumont himself, that the elevating forces, whose activity must be referred to different epochs, have sometimes acted in Europe in parallel lines. ' It is worthy of remark, says that author, that the directions of three systems of mountains, namely, first, that of the Pilas and the Cote d'Or; secondly, that of the Pyrenees; and thirdly, that of the islands of Corsica and Sardinia, are respectively parallel to three other systems, namely, first, that of West· moreland and the Hunsdruck, secondly, that of the Ballons (or Vosges) and the hills of the Bocage, in Calvados; and thirdly, the system of the north of England. The corresponding directions only differ in a few degrees, and the two series have succeeded each other in the same order, leading to the supposition, that there has been a kind of periodical "' The term ' strike ' has been recently adopted by some of our most emineni geologists from the Germa.n ' strcich,' to signify what our miners call the 'line of bearing' of the strata. Such a term was much wanted, and as we often speak of 8t1·iking off in a given direction, the expression seems sufficiently consistent with analogy in our language. 1' Trans. gf De la Beebe's Gegl, Manua11 p. 41. Ch. XXIV.] OF' MOUNTAIN·CIIAINS. 347 recurrence of the same, or nearly the same, directions of elevation*.' Here then we have three systems of mountains, A, B, C, which were formed at successive epochs, and have each a different djrection; and we have three other systems, D, E, F, which, although they are assumed to have the same strike, as the series first mentioned (D corresponding with A, E with B, and F with C), are nevertheless declared to have been formed at different periods. On what principle, then, is the age of an Indian or transatlantic chain referred to one of these European lines rather than another? why is the age of the Alleghanies, or the ghauts of Malabar, determined by their parallelism to B rather than to E, to the Pyrenees rather than to the Ballons of the Vosges? The su'bstance of the last objection has been anticipated by M. Bouet, who, at the same time, disputes the accuracy of many of the facts appealed to by M. de Beaumont. Other errors in fact have also been pointed out by MM. Keferstein, Von Dechen, and De la Beebe:):. But the incorrectness of some of these data might not have affected the validity of the general theory if it had been founded on a solid basis. In regard to the Alps, Ml\1. Necker and Studer have informed me, that on re-examining that chain since de Beaumont's memoirs were published, they have been unable to reconcile the phenomena there exhibited with his views relating to the strike and dip of that great chain. Professor Sedgwick has declared his adhesion to the opinions of de Beaumont; but we are not aware that he had maturely considered them in all their bearings ; and he has stated some important objections to the doctrine of 'parallelism§.' Among others, he has remarked, that in consequence of the spheroidal figure of the earth, different mountain-chains, running north and "' Phil, Mag. and Annals, No. 58, new series, pp. 2551 256. t J ourn. de Geologie, tome iii. p. 338. l Geol. Manual, p. 501, and Second Edition, p. 519. ~ Auniv. Address to the Geol, Soc., Feb., 1831. |
