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Updated: May 24, 2025
In this part of America, however, it may have happened that some of these lakes were caused by partial subsidences, such as were witnessed, during the earthquakes of 1811-12, around New Madrid, in the valley of the Mississippi. By that convulsion the region around Natchez was rudely shaken and much fissured.
Another and less obvious objection to the theory will perhaps be advanced from the circumstance, of the lagoons within atolls and within barrier-reefs never having become in any one instance during prolonged subsidences of a greater depth than sixty fathoms, and seldom more than forty fathoms; but we already admit, if the theory be worth considering, that the rate of subsidence has not exceeded that of the upward growth of the coral on the exterior margin; we are, therefore, only further required to admit, that the subsidence has not exceeded in rate the filling up of the interior spaces by the growth of the corals living there, and by the accumulation of sediment.
Greatly astonished was he at the stories that he heard as to the land around him; how not infrequently great subsidences, extending over very many square miles, took place; and where towns and villages stood when the sun went down, there spread in the morning a sea very many fathoms deep.
Probably there were subsidences of the outer crust, when a portion of the sedimentary deposits was carried down sudden openings." "That may be," I replied; "but if there have been creatures now extinct in these underground regions, why may not some of those monsters be now roaming through these gloomy forests, or hidden behind the steep crags?"
Till her father's return she would have the house to herself, and, the question of the venison despatched, could give herself to long lonely pacings of the empty rooms, and shuddering subsidences upon her pillow. Her first impulse, as the mist cleared from her brain, was the habitual one of reaching out for ultimate relations.
In some places the dangerous expedient of under-cutting the sides had been resorted to to secure a little shelter. Fortunately the undersoil was stiff, the sides of the trenches could be cut quite perpendicular and in fine weather there was slight risk of the under-cutting causing subsidences. Shade from the sun's heat could only be obtained by stretching ground sheets or blankets overhead.
Buddle, "three distinct subsidences were perceptible at the surface, after the clearing out of three seams of coal below, and innumerable vertical cracks were caused in the incumbent mass of sandstone and shale which thus settled down." Section of carboniferous strata at Wallsend, Newcastle, showing "creeps." The upper seam, or main coal, here worked out, was 630 feet below the surface.
Upheavals or subsidences of shores or sea-bottoms, involving deviations of marine currents, remove the habitats of many species to which such currents are salutary or injurious; and further, this redistribution of currents alters the places of sedimentary deposits, and thus stops the burying of organic remains in some localities, while commencing it in others.
At the same time the many and varied elevations and subsidences of portions of the Earth's crust, bringing about the present irregular distribution of land and sea, have entailed modifications of climate beyond those dependent on latitude; while a yet further series of such modifications have been produced by increasing differences of elevation in the land, which have in sundry places brought arctic, temperate, and tropical climates to within a few miles of one another.
But as continents, as large as the spaces supposed to have subsided, have been raised above the level of the sea, as whole regions are now rising, for instance, in Scandinavia and South America, and as no reason can be assigned, why subsidences should not have occurred in some parts of the earth's crust on as great a scale both in extent and amount as those of elevation, objections of this nature strike me as of little force.
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