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Show 340 RELATIVE AN'l'IQUITY (Ch.XXIV. The notion of deluges accompanying the protrusion of mountain-chains is founded on a belief of the instantaneousness of the movement which we are prepared to controvert, and on other assumptions which we have discussed in a former part of this volume*. On these topics, therefore, it will be unnecessary for us to dilate at present, and we shall merely address ourselves to the analysis of that evidence whereby M. de Beaumont endeavours to establish the successive elevation of different mountain-chains, and the supposed law of parallelism in the lines of contemporaneous elevation. M. de Beaumont's proofs that dijferent chains were raised at different epochs.-' We observe,' says l\1:. Elie de Beaumont, 'along nearly aU mountain-chains, when we attentively examine them, that the most recent rocks extend horizontally up to the foot of such chains, as we should expect would be the case if they were deposited in seas or lakes of which these mountains have partly formed the shores; whilst the other sedimentary beds tilted up, and more or less contorted on the flanks of the mountains, rise in certain points even to their highest crests t ,' There are, therefore, in each chain two classes of sedimentary 1·ocks, the ancient or inclined beds, and the newer or horizontal. It is evident that the first appearance of the chain itself was an event ' intermediate between the period when the beds, now upraised, were deposited, and that when the strata were produced horizontally at its feet.' A No. 82. c..f Thus the chain A received its present form after the deposition of the strata b, which have undergone great movements, and before the deposition of the group c, in which the strata have not suffered derangement. * Sec above, p. 148. t Phil. Mag. ancl Annals, No. 58, new series, p. 242. Ch. XXIV.] OF MOUNTAIN·CIIAINS, 341 If we then dis~over another chain, B, in which we find not only the formatiOn b, but the group c also, disturbed and No. 83, ~~~~ y thrown on its edges, we may infer that the latter chain is of subsequent date to A; forB was elevated a•r.ter tl 1 · · ".! • 1 e < epos1t10n of c, and before that of the group d; whereas A originated before the strata c were formed. In order to ascertain whether other mountain ranges are of conte~poraneo.us. date ':ith A and B, or whether they are referrible ~o dzsfznct penods, we have only to inquire whether ~he .geological phenomena are identical, namely, whether the 1nclmed and undisturbed sets of strata correspond to those in the types above mentioned. Objections to M. de Beaumont's tlteory.-Now all this reasoning is perfectly correct, so long as the particular groups of strata.b and c are not confounded with the geological periods to whiCh they may belong, and provided due latitude is given to the term contemporaneous; for it should be understood to all.ude not to a moment of time, but to the interval, whether brief or protracted, which has elapsed between two events, namely, between the accumulation of the inclined and that of the horizontal strata. Bat, unfortunately; the distinct import of the terms c .P • • ' 101- mation and ' period' has been overlooked, or not attended to b~ ~· ~e lleaumont, .an.d hence the greater part of his proofs ate eqmvocal, and lus mferences uncertain; and even if no ~rrors had arisen from this source, the 1eno-th of some of l . t I . . b liS ~n erva .s Is so Immense, that to affirm that all the chains raised m such Intervals were contempm·aneous, is an abuse of language In order to illustrate our argument, Jet us select th~ :yrences as an example. This range of mountains, says M. e Beaumont, rose suddenly (a un seul jet) to its present |