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of both fire and water in the formation of rocks is exemplified not only by results, but also by processes now in action, and the student of nature may watch the steps through the successive changes. He may descend to the boiling pit and witness the operations in the vast laboratory with the same deliberation as he would examine the crucible in a chemist's furnace. Thus the manner in which mountains are made and islands built up becomes a matter of observation. The volcanic dome may be seen in process of accumulation from overflowing lavas, and may be traced as it increases in size. Again, disruptions of the accumulated rock may be observed, followed by their disappearance in the lavas below.
While these volcanic mountains are still extending their limits in one part of the group, in others those changes are finely illustrated, which they undergo through the action of water, gradual decomposition and other allied causes, and these effects are in every stage of progress. In some instances the slopes retain the even surface of the lava stream; in others, they are altered in every feature—the heights are worn down, the whole surface gorged out with valleys, and the depth of these furrowings of time, indicate that the several islands differ widely in the length of the period since they were finished by the fires and left to the action of the elements.
Moreover, the coral formations of the shores present us with reefs now in progress from the growing zoophytes, and there are also reefs elevated many feet above the sea, having a close resemblance to beds of limestone. Besides these, there are hills of drift sandrock, of coral origin. The various facts illustrate, therefore, all the results of coral growth and accumulation.
The group is consequently the key to Polynesian geology. It combines all the features which are elsewhere widely scattered, and they are so exhibited in progressive stages as to afford mutual illustration. An island like Tahiti, so broken into peaks and ridges, may excite wonder and doubt. The Hawaiian group suggests the same difficult problem as Tahiti, but an intelligent solution is at the same time presented for our contemplation and study.
(Dana, Geol., Wilkes' Exp. Expedition.)
Off the west coast of South America there are at least 300 islands, becoming more numerous and in larger groups as we go towards Cape Horn.
Those off the coast of Ecuador, the Albemarle, James, Chatham, Indefatigable, Hood, Charles, Narboro, etc., have already been alluded to in this work, under the head of Galapagos.
Lying near the coast of Peru, and only about twelve miles from the main land, between 13 deg. and 14 deg. south latitude, and containing but a few square miles of area, are the celebrated guano group, the Chincha Islands. It may not be unininteresting to state here, that nearly 20,000,000 tons gauno have been exported to Europe and America from this little group alone. The shipments were commenced in 1841, and continued on a scale of great magnitude up to 1872, when the guano deposits were practically exhausted. Between the years 1853 and 1872, 8,000,000 tons were shipped. It is said that the government of Peru was enriched from this source alone. If we admit Peru as having received #5 per ton for these deposits, it will be seen that bonanzas do not always lie in mineral veins.
As a fertilizer for the agriculturist, guano has no superior—one ton of it being equal to fifteen to thirtyfour tons of the ordinary manures now in use.
There is no doubt but many islands of this character will ultimately be found scattered over the broad expanse of the South Seas. As guano is worth from $30 to $40 per ton in Europe and America, it does not require a great deal of figuring to show that any country or company making a discovery and location of this kind, will not only enrich themselves, but benefit the world at large. The islands of Ferrol, Guanape, Lobos, Tierra, Mengon, Pachacama, San Lorenzo and Zorati, also belonging to Peru, are of some importance.
The larger islands off the west coast of Chili are of great value, not only as important fishing grounds, but for the many agricultural products, and fine timber they produce.
The principal are Byron, Cambridge, Campana, Chiloe, Clarence, Desolation, Duke of York, Guaytecas, Hanover, Huafo, Landfall, Madre de Dios, Mocha, Narborough, Noir, Queen Adelaide, Santa Inez. Skyring and Wellington.
Chiloe is probably the most important, as well as one of the largest of the group, having an area of 5,200 square miles, and inhabited by some 10,000 people. It was first discovered by Mendoza, in 1588. Great attention is paid to agriculture; wheat, corn and potatoes being the favorite crops. With an abundant rainfall, and lands not too mountainous or hilly, Chiloe has long proved a source of wealth to her people. Many vessels, whalers and others, resort to these islands for their supplies, while from many of the islets lying between, considerable quantities of guano are shipped.
Some of the isles were at a former period favorite resorts for the fur seal, but like the islands of Juan Fernandez and Mas a Fuera, which were also great sealing grounds in their day, they have been driven away, and now make their breeding resorts on other groups.
Due west from the northern coast of Chili, something like 2,300 miles, lies this little dot in the Southern Sea. It is located in south latitude 27 deg. 6 min., and west longitude 109 deg. 17 min., contains an area of about seventy square miles, and a population of 1,000 people, of the Polynesian type. Its discovery is sometimes credited to Captain Cook, in 1774, who visited it in that year; by others, to Roggewein, the Dutch navigator, who located and mentions it as early as 1722.
The island is of evident volcanic origin, three prominent craters of past eruptions being already discovered. The soil in the valleys, and some portions fringing the sea shore, is very fertile where placed under cultivation. There is but little forest growth, and water is scarce.
Of late years the island has assumed quite a prominence, from the remarkable features and evidences of a prehistoric race found there, to the great delight of scientists and the sunken continent theorists. Hundreds of statues and broken columns are said to be scattered over the land, some of the former being of the human figure, fully forty feet in height, and eight to ten feet broad across the shoulders. Many have fallen down, and others are rapidly succumbing to the abrading influences of the elements, while others again are found located in the volcanic craters themselves, and thought to indicate the ancient race, as fire worshippers. The rude sculpturing is from the common rock found on the island, many unfinished tablets and statues being discovered in the quarries, as if the inhabitants had been rudely interrupted in their work by some awful volcanic outburst, or earthquake convulsion.