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Show 114 NEWER PLIOCENE PERIOD· [Ch. IX. d ld roceed in the same man-leys by rivers and land-floo s won p . f, • • ner as in modern times in Calabria, _accordmg to our mmer description * · · h f · 1 Before a tract cou ld b e upraised to the .h e.i g t o se. vet af thousand feet a b ove tb e level of the sea, the JOint op.e rat1iO n o runmn. O' water an d subterranean movements mu.s t greatb y mo- 0 1 • 1 raphy. but when the actiOn of t e vol-dify the P 1YSICa geog ' ' . '1 . cam.e forces 11 as b een sus pended ' when a periOd of tranq. m hty succeeds, an d t 11 e 1e ve1 s o f the land remain fixed and statiOnary, the erosi·v e power. o f wa ter must soon be reduced to a state of comparati· ve eqm'1i' b rm· m · For this reason, a co. untry that .h as been rai·s e d a t a ver.Y remote period to a considerable height above t h e 1e ve1 o f the sea ' may present nearly the same e.x ternal con fi gurati·o n as one that has been more recently uphfted to the same height. . . In oth er word s, the time required for the raismg of a mass ~f land to the height of several hundred yards. mu.st usually be so enormous ( assu mi. nO0 ' as we do that the operatio•n Is effected by ord m. ary vo1 c am· c forces) ' that the aqueous and 1gneous .a gents will have time before the elevation is completed to mod~fy the sur1ea ce, an d I' mpr·I'nt thereon the ordinary forms of htll and va1 1 ey, b y w 11ich our continents are diversified. But· after th1e cessation of earthquakes these causes of change will reman d or. mant , or nearly so. The greater part, therefore, o.f .th e earth's surface will at each period be at rest, simply retmm~g the features already imparted to it, while smaller tracts ~111 assume, as they rise successively from the deep, a configuratiOn perfectly analogous to that by which the more ancient lands were previously distinguished. . Migration of animals and plants.-The changes which, according to the views already explained, have b~en brought about in the earth's crust by the agency of vol~amc heat, cannot fail to strike the imagination, when . we constder how recent in the calendar of nature is the epoch to which we refer them. }3ut if we turn our thoughts to the organic world, we shall feel, "' Chai'· ~J~;iv, Ch. IX.] SPECIES OLDER TIIAN THEIR STATtONS, 115 perhaps, no less surprise at the great vicissitude which it has undergone during the same period. We have seen that a large portion of Sicily has been converted from sea to land since the Mediterranean was peopled with the living species of testacea and zoophytes. The newly emerged surface, therefore, must, during this modern zoological epoch, have been inhabited for the first time with the terrestrial plants and animals which now abouud in Sicily. It is fair to infer, that the existing terrestrial species are, for the most part, of as high antiquity as the marine, and if this be the case, a large proportion of the plants and animals, now found in the tertiary districts in Sicily, must have inhabited the earth before the newer Pliocene strata were raised above the waters. The plants of the Flora of Sicily are common, almost without exception, to Italy or Africa, or some of the countries surrounding the Mediterranean*, so that we may suppose the greater part of them to have migrated from pre-existing lands, just as the plants and animals of the Phlegrrean fields have colonized Monte N uovo, since that mountain was thrown up in the sixteenth century. We arc brought, therefore, to admit the curious result, that the flora and fauna of the Val di Noto, and some other mountainous regions of Sicily, are of higher antiquity than the countt ·y itself, having not only flourished before the lands were t·aised from the deep, but even before they were deposited beneath the waters. Such conclusions throw a new HO'ht on the 0 adaptation of the attributes and migratory habits of animals and ~}ants, to the changes which are unceasingly in progress in the lnanimate world. It is clear that the duration of species is so great, that they are destined to outlive many important revolutions in the physical geography of the earth, and hence those innumerable contrivances for enabling the subjects of the animal and vegetable creation to extend their range, the inhabitants . ~ P~of~ssor Viviani of Genoa informed me, that, considering the great extent of Stctly, It was remarkable that its flora produced scarcely any, if any peculia 1 • indi· ?P.Iwus species, whe1·eas there are several in Cor11ica 1 and some other McditerraneaQ ~~lands, I 2 |