Particulars respecting the Volcanoes in the Andes, and the Fishes thrown out by them.

By M.

Von Humboldt.

T HE chain of the Andes, extending more than 2000 leagues, from the Straits of Magellan to the northern shores which border on Asia, contains above fifty volcanoes still active, of which the phenomena are as various as their height and local situation.

A small number of the least elevated of these volcanoes throw out running lava.

I have seen, at the volcano of Zurullo, in Mexico, a basaltic cone that sprung from the earth the 15th of September 1759, and at present rising 1593⅔ feet above the surrounding plain.

The volcanic ridges of Guatimala cast out a prodigious quantity of muriat of ammonia.

Those of Popayan and the high plain of Pasto contain either solfatares, which exhale sulphureous acid, or little craters filled with boiling water, and disengaging sulphurated hydrogen, which decomposes by contact with the oxygen of the atmosphere.

The volcanoes of the kingdom of Quito throw out pumice stone, basaltes, and scorified porphyries; and vomit enormous quantities of water, carburetted argil, and muddy matter, which spreads fertility from eight to ten leagues around.

But since the period to which the traditions of the natives ascend, they have never produced great masses of running melted lava.

The height of these colossal mountains, being five times greater than that of Vesuvius, and their inland situation are, no doubt, the principal causes of these anomalies.

The subterranean noise of Cotopaxi during its great explosions, extends as far as the distance between Vesuvius and Dijon.

But not withstanding this prodigious force, it is known, that if the volcanic fire was at a great depth, the melted lava could neither raise itself to the edge of the crater, nor pierce the flank of these mountains, which, to the height of 8970 feet, are fortified by high surrounding plains.

It appears, therefore natural, that volcanoes so elevated should discharge from their mouth only detached stones, volcanic cinders or ashes, flames, boiling water, and, above all, this carburetted argil impregnated with sulphur, that is called moga in the language of the country.

The mountains of the kingdom of Quito sometimes offer to the naturalist another spectacle less alarming, but not less curious.

The great explosions are periodical, and somewhat rare.

Cotopaxi, Tungurahua, and Sangay, sometimes do not present one in twenty or thirty years.

But during such intervals, even these volcanoes will discharge enormous quantities of argillaceous mud; and, what is more extraordinary, an innumerable quantity of fish.

By accident, none of these volcanic inundations took place the year that I passed the Andes of Quito; but the fish vomited from the volcanoes is a phenomenon so common, and so generally known by all the inhabitants of that country, that there cannot remain the least doubt of its authenticity.

As there are in these regions several very well informed persons, who have successfully devoted themselves to the physical sciences, I have had an opportunity of procuring exact information respecting these fishes. M. de Larrae, at Quito, well versed in the study of chemistry, who has formed a cabinet of the minerals of his country, has been particularly useful to me in these researches.

Examining the archives of several little towns in the neighbourhood of Cotopaxi, in order to extract the epochs of the great earthquakes, that fortunately have been preserved with care, I there found some notes on the fish ejected from the volcanoes.

On the estates of the Marquis of Selvalegre the Cotopaxi had thrown a quantity so great, that their putrefaction spread a fetid odour around.

In 1691, the almost extinguished volcano of Imbaburu threw out thousands on the fields in the environs of the city of Ibarra.

The putrid fevers which commenced at that period were attributed to the miasma which exhaled from these fish, heaped on the surface of the earth, and exposed to the rays of the sun.

The last time that Imbaburu ejected fish, was on the 19th of June 1798, when the volcano of Corgneirazo sunk, and thousands of these animals, enveloped in argillaceous mud, were thrown over the crumbling borders.

The Cotopaxi and Tungurahua throw out fish, sometimes by the crater which is at the top of these mountains, sometimes by lateral vents, but constantly at 15,000 or 16,000 feet above the level of the sea: the adjacent plains being 9000 feet high, we may conclude that these animals issue from a point which is 9000 feet higher than the plains on which they are thrown.

Some Indians have assured me that the fish thrown out by the volcanoes were sometimes still alive, as they descended along the flank of the mountain: but this fact does not appear to me sufficiently proved: certain it is that among the thousands of dead fish that in a few hours are seen descending from Cotopaxi with great bodies of cold fresh water, there are very few that are so much disfigured that we can believe them to have been exposed to the action of a strong heat.

This fact becomes still more striking, when we consider the soft flesh of these animals, and the thick smoke which the volcano exhales during the eruption.

It appeared to me of very great importance to descriptive natural history to verify sufficiently the nature of these animals.

All the inhabitants agree that they are the same with those which are found in the rivulets at the foot of these volcanoes, and called prennadillas: they are even the only species of fish that is discovered at the height of above 7 500 toises, in the waters of the kingdom of Quito. M. Lacepede, who has also examined it, advised me to place it in that division of Silurus, which, in the fifth volume of his natural history of fishes, he has described under the name of pimelodes.

From the enormous quantity of Pimelodes the volcanoes of the kingdom of Quito occasionally discharge, we cannot doubt, that this country contains great subterranean lakes which conceal these, for in the little rivers around there are very few.

A part of those rivers may communicate with the subterranean pits; it is also probable that the first pimelodes which have inhabited these pits have mounted there against the current.

I have seen fish in the caverns of Derbyshire in England; and near Gailenreath, in Germany, where the fossil heads of bears and lions are found, there are living trouts in the grottoes, which at present are very distant from any rivulet, and greatly elevated above the level of the neighbouring waters.

In the province of Quito, the subterraneous roarings that accompany the earthquakes; the masses of rocks that we think we hear crumbling down below the earth we walk on; the immense quantity of water that issues from the earth during the volcanic explosions, and numerous other phenomena, indicate that all the soil of this elevated plain is undermined.

But, if it is easy to conceive that vast subterranean basins may be filled, it is more difficult to explain how these animals are attracted by volcanoes that ascend to the height of 9000 feet, and discharged either by their craters or by their lateral vents.

Should we suppose that the pimelodes exist in subterranean basins of the same height at which they are seen to issue?

How conceive their origin in a position so extraordinary; in the flank of a cone so often heated, and perhaps partly produced by volcanic fire?

Whatever may be the source from which they issue, the perfect state in which they are found induces us to believe that those volcanoes, the most elevated and the most active in the world, experience from time to time, convulsive movements, during which the disengagement of caloric appears less considerable than we should suppose it. Earthquakes do not always accompany those phenomena.

The corregidor of the city of Ibarra, Don José Pose Pardo, has communicated to me an interesting observation on the pimelodes.

„It is known (says he in a letter which I have still preserved,) that the volcano of Imbaburu, at the time of its great eruption on the side next our city, threw out an enormous quantity of prennadillas; it even continues still occasionally to do so, especially after great rains.

It is observed, that these fishes actually live in the interior of the mountain, and that the Indians of St Pabla fish for them in a rivulet at the very place whence they issue from the rock.

The fishery does not succeed either in the day or in moonlight: a very dark night is therefore necessary, as the prennadillas will not otherwise come out of the volcano, the interior of which is hollow.”

It appears then that the light is injurious to these subterraneous fishes, which are not accustomed to so strong a stimulus; an observation so much the more curious, that the pimelodes of the same species, which inhabit the brooks in the vicinity of the city of Quito, live exposed to the brightness of the meridian sun.