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“Yon dreary plain, forlorn and wild,
We have in the preceding chapters given somewhat in detail an account of the various aqueous causes of change, now in operation. We sh: Il consider in the present chapter the igneous causes of chang , or volcanic action; and in order to economise the little space we can allow, will consider them as follows. First, we shall give a sketch of the geographical distribution of the chief volcanoe now active, or which have been active within the historic era. We shall next give an account of the principal earthquakes, nd other volanic phenomena which have disturbed . the earth's so face; and lastly, consider such changes, supposed to be due to internal igneous agency, as the gradual elevation and depression of various tracts of country. It would be out of place for us to discuss at pres&nt, the question, whether the interior of the globe is in a state of fusion, and that the eruptive force of volcanoes is the occasional liberation of the molten mass, acted upon by the intense pressure of the superincumbent strata, or by confined gases and vapors; or whether the intense heat which melts masses of rock, causing the most violent convulsions, is caused by chemical action, i. e. the union of oxygen derived from water or the air, with the metallic bases of the earths and alkalies, forming silica, alumina, lime, soda, &c., substances which predominate in lavas; or whether it be a union of both these causes. In our own opinion it is neither, but is the result of simple mechanical action, produced in a manner we cannot here describe. Volcanoes are found distributed all over the surface of the earth, though more prevalent in some portions than in others. Many of the islands in the Pacific and Atlantic are of volcanic origin; perhaps the majority of them. In some parts of the earth volcanoes stand alone, but they are mostly connected with extensive mountain ranges, extending in a linear direction, and we may select three distinct regions of subterranean disturbance. The most extensive is that of the Andes. Along the whole western shores of North and South America, extends a lofty mountain chain, remarkable not only for its position, but also for its collosal form, the nature of the masses of which it is composed, and of the materials ejected. Along the whole extent of this chain, volcanoes occur, and between the 46th deg. of south latitude to the 27th deg. is a line of volcanoes so uninterrupted that scarcely a degree is passed without the occurrence of one of these in an active state; about twenty now active are enumerated in this space, and doubtless there are very many more which have been active at a recent period. When we remember how long a time Vesuvius had remained quiet, before it again renewed its activity, and overwhelmed the cities of Herculaneum and Pompeii, we can readily admit that the number of volcanic vents or craters is much greater than really is now apparent. The immense height of the volcanic mountains of the Andes and Cordilleras is very remarkable, and the craters are all formed by bursting through porphyritic rock, or igneous unstratified rock, containing crystals of feldspar. Some of the loftiest summits are composed of trachyte, a rock of igneous origin, unstratified and allied to the trap rocks, such as basalt, greenstone, &c. On the summits are found large quantities of obsidian, or dark green volcanic glass, pumice stone; and tuff formed out of cinders, and fragments of lava cemented together. It appears highly probable that a chain of volcanic vents extends quite around the globe, in the general direction north and south. A lofty chain of mountains was discovered by Capt. J. C. Ross, in the Antarctic regions in year 1841, at a distance of
volcano Es. 237
about 800 miles from the south pole. Two of the loftiest of these were named from his vessels, Mount Erebus, and Mount Terror, they are each about 12,000 feet in height, and the former is an active volcano. This range of mountains is probably connected by a submarine chain with the Andes, first appearing in Terradel-Fuego, near which Capt. Basil Hall is said to have witnessed volcanic eruptions. As we proceed north along the western shore of South America, we find in Chili, a large number of active volcanoes, and, what we might reasonably expect, the country continually disturbed by earthquakes, and abounding in hot springs. Willarica is the principal of the Chilian volcanoes, it burns without intermission, and is so high that it may be seen at a distance of 150 miles. It is said that a year never passes in this province, without some slight shocks of earthquakes, and sometimes the most tremendous convulsions occur. As we proceed northward, we find one active volcano in Peru, but earthquakes are so common that scarce a week passes without them; and the names of Lima, and Callao, are familiar in this connection. Proceeding still farther north, the mountains increase in height, and furnish by the melting of their accumulated snows, and the moisture which is precipitated from the trade winds which blow over the warm region of Brazil, the sources of that magnificent river, the Amazon, which continually pours such a flood of water into the Atlantic. When we arrive in the neighborhood of Quito, in Equador, we find numerous and very lofty volcanoes, no less than six being embraced in a space of five degrees; commencing at the second degree of south latitude, and proceeding to the third degree of north latitude — One of these volcanoes, Cotopaxi, arises to the height of 18,867 feet, and is the highest volcanic summit of the Andes. In form it is a perfect cone, usually covered with an enormous bed of snow. On next page, we give an engraving which represents this celebrated volcano, which is higher than Vesuvius would be, if placed on the top of Teneriffe. The smooth cone, crested with the purest white, shines in the rays of the sun with dazzling splendor, and detaches itself from the azure vault of heaven in the most picturesque manner. At night, smoke and fire are seen rising from its summit, like a K*
beacon of flame in the regions above. In the course of the last century it had five great eruptions; in one of these, in January
1803, the snows were dissolved in one night, pouring a deluge of waters over the plains below. It is averred that the eruptions of Cotopaxi have been heard at a distance of 600 miles, and Humboldt states that at 140 miles distance on the coast of the Pacific, it sounded like thunder. The substances ejected from these lofty craters are pumice, and cinders, rarely lava currents; on account of their immense heights, and the consequent enormous pressure which is required to raise a solid molten mass. Torrents of mud and boiling water are erupted, and subterranean cavities containing water are opened, and vast quantities of mud, volcanic sand, and loose stones, are carried down to the regions below. Mud derived from this source, in the year 1797, descended from the sides of Tunguragua, a volcano in the neighborhood of Cotopaxi, and filled valleys 1000 feet wide to the depth of 600 feet. In these currents and lakes are thousands of small fish, which, according to Humboldt, have lived and multiplied in the subterranean lakes. So great a quantity of these fish were eruptedin 1690, from the volcano of Imbaburu, that fevers were caused by effluvia arising from the putrid animal matter. Sometimes,after successive eruptionss the undermined walls of the mountain fall. and it becomes a mass of ruins, such was the fate of L’Altar, which was once higher than Chimborazo, but according to the tradition of the natives, before the discovery of America, a prodigious eruption took place which lasted eight years and broke it down. VolcANors. 239
In 1698 another lofty volcano fell, with a tremendous crash. Proceeding farther north, we find three active volcanoes in the province of Pasto, and three likewise in that of Popayan. Passing on, across the isthmus of Darien into Guatemala, and Nicaragua, no less than twenty-one active wolcanoes are found between the tenth and fifteenth degrees of noi th latitude. Among these is an enormous mountain called the volcano of water (de Agua), at the base of which in 1527, the old city of Guatemala was built. A few years afterward, a most formidable aqueous eruption burst forth, which overwhelmed the whole city, and buried in the ruins most of the inhabitants. Appalled by this disaster, the Spaniards built another city, New Guatemala, in another situation, farther from the mountain. Among other splendid buildings it contained a Cathedral more than 300 feet long, and one of its nunneries had more than 1000 persons in it. After a series of dreadful shocks, and volcanic eruptions, this beautiful city shared the fate of the former, and was reduced to a heap of Iuins in 1775. We have now traced this volcanic chain for a distance of nearly 5000 miles from south to north, arriving at the high table land of Mexico, which is the middle part of the great chain of mountains called the Andes or Cordilleras in the south, and the Rocky Mountains in the north. This table land is from 6000 to 8000 feet in height," thus rivalling Mount St. Bernard and other remarkable summits in the eastern continent. This table land is not an interval between opposite ridges, but is the highest part of the ridge itself. In the course of it, isolated peeks occur, the summits of which reach the elevation of perpetual snow. It is somewhat remarkable, that a chain of volcanic mountains traverses this table land at right angles, which, with few interruptions, seems almost as smooth as the ocean, to a distance of 1500 miles north. Hence while communication with the City of Mexico is very difficult from either sea coast, there is nothing to prevent wheel carriages from running along the top of this mountain chain to Santa Fe. The volcanic mountains, are five in number, and run at right angles; commencing with the most eastern, we have Tuxtla, a few miles west of Vera Cruz; Orizava, the height of which is 17,370 feet; Popocatepetl 500 feet higher, and shown in the engraving below.