United States or Niue ? Vote for the TOP Country of the Week !
The talk, of course, has its paroxysms and its subsidences. I have once or twice found myself on a sudden in total silence in the middle of a somewhat prolix, though humorous story, commenced in an uproar for the sole recreation of my pretty neighbour, and ended patched up, renounced a faltering failure, under the converging gaze of a sternly attentive audience.
As we see that in those parts of the ocean, where coral-reefs are most abundant, one island is fringed and another neighbouring one is not fringed; as we see in the same archipelago, that all the reefs are more perfect in one part of it than in another, for instance, in the southern half compared with the northern half of the Maldiva Archipelago, and likewise on the outer coasts compared with the inner coasts of the atolls in this same group, which are placed in a double row; as we know that the existence of the innumerable polypifers forming a reef, depends on their sustenance, and that they are preyed on by other organic beings; and, lastly, as we know that some inorganic causes are highly injurious to the growth of coral, it cannot be expected that during the round of change to which earth, air, and water are exposed, the reef-building polypifers should keep alive for perpetuity in any one place; and still less can this be expected, during the progressive subsidences, perhaps at some periods more rapid than at others, to which by our theory these reefs and islands have been subjected and are liable.
The tide is scarcely perceptible, and the currents are very slight. The land is still sinking, as is proved by the Roman sarcophagi found beneath the water at Vranjic and the submerged roads between Aquileia and Grado; while there are records of the destruction of ancient towns from sudden subsidences, as that of Cissa, near Rovigno.
We may suppose that the transference of molten matter from one region to another may be among the causes of slow subsidences and elevations. Intrusions give rise to fissures, dikes, and intrusive sheets, and these dislocations cannot fail to produce earthquakes.
It was a gloomy place, that mine, and opened out into strange cavernous places, eaten away by water, or by strange crackings and subsidences of the earth, in the far distant ages when the boiling springs of the volcanic regions were depositing the beds of tufa, here of immense thickness, springs which are still in evidence, but no longer to pour out waters that scald, but of a gentle lukewarm or tepid temperature, which go on depositing their suspended stone to this day, though in a feeble, sluggish manner.
And this broad statement holds good for the whole of that time, even though it was not without its minor changes, its new forms of animal and vegetable life, its variations of level, its upheavals and subsidences; for, nevertheless, through its whole duration, it was the age of low detached lands, it was the age of Cryptogams, it was the age of Fishes.
Each region of the Earth's surface has its special history of elevations, subsidences, periods of rest: and this history in no case fits chronologically with the history of any other portion. River deltas are now being thrown down on formations of different ages: some very ancient, some quite modern.
Not that I can recall any memorable peculiarities; for the country, most of the way, is a succession of the gentlest swells and subsidences, affording wide and far glimpses of champaign-scenery here and there, and sinking almost to a dead level as we draw near Stratford.
In the deltas of many large rivers, such as the Po, the Nile, the Ganges, and the Mississippi, buried soils prove subsidences of hundreds of feet; and in several cases, as in the Mississippi delta, the depression seems to be now in progress. Other proofs of the same movement are drowned land forms which are modeled only in open air.
Considering that the salt lies often a hundred and fifty yards deep, and that these pillars have to bear the weight of all that depth of solid rock, it is not surprising that subsidences should sometimes occur in abandoned shafts, where the water is allowed to collect, and slowly dissolve away the supporting columns.
Word Of The Day