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Show ~64 CITIES SUBMERGED AND IMBEDDED [Ch.XVI. "It is a curious question," he adds, "how the crystals were formed in the helmet, and on the adhering calcareous deposit. There being no reason to suppose deposition from solution, are we not under the necessity of inferring, that the mineralizing process depends on a small motion a~d sep~r.ation of the particles of the original compound? Tlus. mot10n may h:ve been due to the operation of electro-chemical powers winch may have separated the different metals of the alloy.'' Effects of the Subme·rsion of Land by Ea·rthquakes. We have hitherto considered the transportation of plants and animals from the land by aqueous agents, and their inhumation in lacustrine or submarine deposits, and we may now inquire what tendency the subsidence of tracts of land by ea·rthquakes may have to produce analogous effects. Several examples of the sinking down of buildings and portions of towns near the shore to various depths beneath the level of the sea, during subterranean movements, were enumerated in a former volume, when we treated of the changes brought about by ino1·ganic causes. The -events alluded to were comprised within a brief portion of the historical period, and confined to a small number of the regions of active volcanos. Y ct these authentic facts, relating merely to the last century and a half, gave indications of considerable change which must have taken place in the physical geography of the globe. If, during the earthquake of Jamaica in 169~, some of the houses in Port Royal subsided, together with the ground they stood upon, to the depth of twenty-four, thirty-six and forty-eight feet under water, we are not to suppose that this was the only spot throughout the whole range of the coasts of that ~sl:nd or the bed of the surrounding sea which suffered Similar depressions. If the quay at Lisbon sank at once to the dept!l of six hundred feet in 1755, we must not imagine that tlus was the only point on the shores of the peninsula where simi .. lar phenomena might have been witnessed. If dudng the short period since South America has been Oh. XVI.] IN SUBAQUEOUS DEPOSIT~. 9l65 colonized by Europeans we have proof of alterations of level at the three principal ports on the western shores, Callao*, Valparaiso.' ~nd Co~ception, we cannot for a moment suspect that these c1t1es so d1stant from each other have been selected as the peculiar points where the desolating power of the earthquake has expended its chief fury. "It would be a knowing arrow that could choose out the brave men from the cowards," retorted the young Spartan, when asked if his comrades who had fallen on the field of battle were braver than he and his fellow prisoners ; we might in the same manner remark that a geologist must attribute no small discrimination and malignity to the subterranean force, if he should suppose it to spare habitually a line of coast many thousand miles in lenoth with b ' the exception of those few spots where populous towns have been erected. If then we consider how small is the area occupied by the sea-ports of this disturbed region,-points where alone each slight change of the relative level of sea and land can be recognized, and reflect on the proofs in our possession of the local revolutions that have happened on the site of each port, within the last century and a half, our conceptions must be greatly exalted respecting the magnitude of the alterations which the Andes may have undergone even in the course of the last six thousand years. We cannot better illustrate the manner in which a large extent of surface may be submerged, so that the terrestrial plants and animals may become imbedded in subaqueous strata, than by referring to the earthquake of Cutch, in 1819, alluded to by us in a former volume t. We shall enter somewhat more fully into details concerning that catastrophe than the · * It is well known that during the great earthquake of Lima, in 17 4 6, part of the promontory south of Callao sank down, and it is a common story at Lima that its former termination became the present isle of San Lorenzo, between which and the main land there is now a navigable channel. The submerged arches of a church, and the present position of oth01· buildings, are said to indicate that the site of Callao underwent, during the earthquakes, a change of level; an interesting fact, the evidences of which we hope will soon be examined by some of our naval officers, and other intelligent persons frequenting that port. t Vol, i. p. ~05, |