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Show 478 CONCLUDING REMARKS. Although it would be rash to attempt to confirm these speculations by reference to the scanty observations hitherto made on the effects of earthquakes, yet we cannot but remarl<, that the instances of subsidence on record arc far more numerous than are those of elevation. ,.rhose writers who have most strenuously contended for the analogy of the effects of earthquakes in ancient and modern times, have nevertheless declared that the energy of the force has considerably abated. But they do not appear to have been aware that, in order to adduce plausible grounds for such an hypothesis, they must possess a most extensive knowledge of the economy of the whole terrestrial system. We can only estimate the relative amount of change produced at two distinct periods, by a particular cause in a given lapse of time, when we have obtained some common standard for the measurement of equal portions of time at both periods. We have shown that, within the last one hundred and forty years, some hundred thousand square miles of territory have been upheaved to the height of several feet, and that an area of equal, if not greater extent, has been depressed. Now, they who contend, that formerly more movement was accomplished by earthquakes in the space of one hundred and forty years, must first explain the measure of time referred to, for it is obvious that they cannot in geology avail themselves of the annual revolution of our planet round the sun. Suppose they assume that the power of volcanos to emit lava, and of running water to transport sediment from one part of the globe to the other, has remained uniform from the earliest periods, they might then attempt to compare the effects of subterranean movements in ancient and modern times by reference to one common standard, and to show that, while a certain number of lava-currents were produced, or so many cubic yards of sediment accumulated, the elevation and depression of the earth's crust were once much greater than they are now. Or, if they should declare that the progressive rate of change of species in the animal and vegetable kingdoms had always been uniform, they might then endeavour to disparage the degree of energy now exerted by earthquakes, by showing that, in relation to the mutations of assemblages of organic species, earthquakes had become comparatively feeble. But our present scanty acquaintance, both CONCLUDING REMARKS. 479 with the animate and m. am.m ate w ld b mnt such generali'zat'I Ons . nor h or h' can h Y no means war-gradual decline of the 't. . ave t ey w o contend for the support such a line of a.c 1v1ty of nat ura1 agents, attempted to ai gument Th t . l mature, in the present stat f · a It wou d be most pre- . e o natural h · t t comparative rate of fiuctuat' . h ts ?ry, o reason on the in ancient and modern tim Ion ~~1 tb e species of organic beings when we proceed in the nex~sd.w.1 • e more fully demonstrated the intimate con~exion bet lVISionl of our subject, to consider present condition of th .weeln geo ogy, and the study of the . e amma and vegetable kin doms To conclude : It appears from th . g · respecting the agency of s'ubte e views above explained, rranean movem t h constant repair of the dry land d 1 b en s, t at the ' an t 1e su servi f planet to the support of terrestrial as well e~cy o ~ur are secured by the e]evating and d . as aquatic species, quakes. This cause, so often the soepr~ssi;g power of earththe inhabitants of the globe whi'ch ~r~te o. death and terror to ' VISI s m succes · zone, and fills the earth with monument; f . sdiOdn~ every · h I 0 rum an Isorder Is, nevert e ess, a conservative principle in the hio-hest de ' and, above all others, essential to the stabi'l't f oh gree, 1 Yo t e system, |