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- Equinoctial Regions of America V2 - 4/97 -


Valencia.

It is impossible to anticipate the limits, more or less narrow, to which this basin of water will one day be confined, when an equilibrium between the streams flowing in and the produce of evaporation and filtration, shall be completely established. The idea very generally spread, that the lake will soon entirely disappear, seems to me chimerical. If in consequence of great earthquakes, or other causes equally mysterious, ten very humid years should succeed to long droughts; if the mountains should again become clothed with forests, and great trees overshadow the shore and the plains of Aragua, we should more probably see the volume of the waters augment, and menace that beautiful cultivation which now trenches on the basin of the lake.

While some of the cultivators of the valleys of Aragua fear the total disappearance of the lake, and others its return to the banks it has deserted, we hear the question gravely discussed at Caracas, whether it would not be advisable, in order to give greater extent to agriculture, to conduct the waters of the lake into the Llanos, by digging a canal towards the Rio Pao. The possibility* of this enterprise cannot be denied, particularly by having recourse to tunnels, or subterranean canals. (The dividing ridge, namely, that which divides the waters between the valleys of Aragua and the Llanos, lowers so much towards the west of Guigue, as we have already observed, that there are ravines which conduct the waters of the Cano de Cambury, the Rio Valencia, and the Guataparo, in the time of floods, to the Rio Pao; but it would be easier to open a navigable canal from the lake of Valencia to the Orinoco, by the Pao, the Portuguesa, and the Apure, than to dig a draining canal level with the bottom of the lake. This bottom, according to the sounding, and my barometric measurements, is 40 toises less than 222, or 182 above the surface of the ocean. On the road from Guigue to the Llanos, by the table-land of La Villa de Cura, I found, to the south of the dividing ridge, and on its southern declivity, no point of level corresponding to the 182 toises, except near San Juan. The absolute height of this village is 194 toises. But, I repeat that, farther towards the west, in the country between the Cano de Cambury and the sources of the Rio Pao, which I was not able to visit, the point of level of the bottom of the lake is much further north.) The progressive retreat of the waters has given birth to the beautiful and luxuriant plains of Maracay, Cura, Mocundo, Guigue, and Santa Cruz del Escoval, planted with tobacco, sugar-canes, coffee, indigo, and cacao; but how can it be doubted for a moment that the lake alone spreads fertility over this country? If deprived of the enormous mass of vapour which the surface of the waters sends forth daily into the atmosphere, the valleys of Aragua would become as dry and barren as the surrounding mountains.

The mean depth of the lake is from twelve to fifteen fathoms; the deepest parts are not, as is generally admitted, eighty, but thirty-five or forty deep. Such is the result of soundings made with the greatest care by Don Antonio Manzano. When we reflect on the vast depths of all the lakes of Switzerland, which, notwithstanding their position in high valleys, almost reach the level of the Mediterranean, it appears surprising that greater cavities are not found at the bottom of the lake of Valencia, which is also an Alpine lake. The deepest places are between the rocky island of Burro and the point of Cana Fistula, and opposite the high mountains of Mariara. But in general the southern part of the lake is deeper than the northern: nor must we forget that, if all the shores be now low, the southern part of the basin is the nearest to a chain of mountains with abrupt declivities; and we know that even the sea is generally deepest where the coast is elevated, rocky, or perpendicular.

The temperature of the lake at the surface during my abode in the valleys of Aragua, in the month of February, was constantly from 23 to 23.7 degrees, consequently a little below the mean temperature of the air. This may be from the effect of evaporation, which carries off caloric from the air and the water; or because a great mass of water does not follow with an equal rapidity the changes in the temperature of the atmosphere, and the lake receives streams which rise from several cold springs in the neighbouring mountains. I have to regret that, notwithstanding its small depth, I could not determine the temperature of the water at thirty or forty fathoms. I was not provided with the thermometrical sounding apparatus which I had used in the Alpine lakes of Salzburg, and in the Caribbean Sea. The experiments of Saussure prove that, on both sides of the Alps, the lakes which are from one hundred and ninety to two hundred and seventy-four toises of absolute elevation* (* This is the difference between the absolute elevations of the lakes of Geneva and Thun.) have, in the middle of winter, at nine hundred, at six hundred, and sometimes even at one hundred and fifty feet of depth, a uniform temperature from 4.3 to 6 degrees: but these experiments have not yet been repeated in lakes situated under the torrid zone. The strata of cold water in Switzerland are of an enormous thickness. They have been found so near the surface in the lakes of Geneva and Bienne, that the decrement of heat in the water was one centesimal degree for ten or fifteen feet; that is to say, eight times more rapid than in the ocean, and forty-eight times more rapid than in the atmosphere. In the temperate zone, where the heat of the atmosphere sinks to the freezing point, and far lower, the bottom of a lake, even were it not surrounded by glaciers and mountains covered with eternal snow, must contain particles of water which, having during winter acquired at the surface the maximum of their density, between 3.4 and 4.4 degrees, have consequently fallen to the greatest depth. Other particles, the temperature of which is +0.5 degrees, far from placing themselves below the stratum at 4 degrees, can only find their hydrostatic equilibrium above that stratum. They will descend lower only when their temperature is augmented 3 or 4 degrees by the contact of strata less cold. If water in cooling continued to condense uniformly to the freezing point, there would be found, in very deep lakes and basins having no communication with each other (whatever the latitude of the place), a stratum of water, the temperature of which would be nearly equal to the maximum of refrigeration above the freezing point, which the lower regions of the ambient atmosphere annually attain. Hence it is probable, that, in the plains of the torrid zone, or in the valleys but little elevated, the mean heat of which is from 25.5 to 27 degrees, the temperature of the bottom of the lakes can never be below 21 or 22 degrees. If in the same zone the ocean contain at depths of seven or eight hundred fathoms, water the temperature of which is at 7 degrees, that is to say, twelve or thirteen degrees colder than the maximum of the heat* of the equinoctial atmosphere over the sea, I think it must be considered as a direct proof of a submarine current, carrying the waters of the pole towards the equator. (* It is almost superfluous to observe that I am considering here only that part of the atmosphere lying on the ocean between 10 degrees north and 10 degrees south latitude. Towards the northern limits of the torrid zone, in latitude 23 degrees, whither the north winds bring with an extreme rapidity the cold air of Canada, the thermometer falls at sea as low as 16 degrees, and even lower.) We will not here solve the delicate problem, as to the manner in which, within the tropics and in the temperate zone, (for example, in the Caribbean Sea and in the lakes of Switzerland,) these inferior strata of water, cooled to 4 or 7 degrees, act upon the temperature of the stony strata of the globe which they cover; and how these same strata, the primitive temperature of which is, within the tropics, 27 degrees, and at the lake of Geneva 10 degrees, react upon the half-frozen waters at the bottom of the lakes, and of the equinoctial ocean. These questions are of the highest importance, both with regard to the economy of animals that live habitually at the bottom of fresh and salt waters, and to the theory of the distribution of heat in lands surrounded by vast and deep seas.

The lake of Valencia is full of islands, which embellish the scenery by the picturesque form of their rocks, and the beauty of the vegetation with which they are covered: an advantage which this tropical lake possesses over those of the Alps. The islands are fifteen in number, distributed in three groups;* without reckoning Morro and Cabrera, which are already joined to the shore. (* The position of these islands is as follows: northward, near the shore, the Isla de Cura; on the south-east, Burro, Horno, Otama, Sorro, Caiguira, Nuevos Penones, or the Aparecidos; on the north-west, Cabo Blanco, or Isla de Aves, and Chamberg; on the south-west, Brucha and Culebra. In the centre of the lake rise, like shoals or small detached rocks, Vagre, Fraile, Penasco, and Pan de Azucar.) They are partly cultivated, and extremely fertile on account of the vapours that rise from the lake. Burro, the largest of these islands, is two miles in length, and is inhabited by some families of mestizos, who rear goats. These simple people seldom visit the shore of Mocundo. To them the lake appears of immense extent; they have plantains, cassava, milk, and a little fish. A hut constructed of reeds; hammocks woven from the cotton which the neighbouring fields produce; a large stone on which the fire is made; the ligneous fruit of the tutuma (the calabash) in which they draw water, constitute their domestic establishment. An old mestizo who offered us some goat's milk had a beautiful daughter. We learned from our guide, that solitude had rendered him as mistrustful as he might perhaps have been made by the society of men. The day before our arrival, some hunters had visited the island. They were overtaken by the shades of night; and preferred sleeping in the open air to returning to Mocundo. This news spread alarm throughout the island. The father obliged the young girl to climb up a very lofty zamang or acacia, which grew in the plain at some distance from the hut, while he stretched himself at the foot of the tree, and did not permit his daughter to descend till the hunters had departed.

The lake is in general well stocked with fish; though it furnishes only three kinds, the flesh of which is soft and insipid, the guavina, the vagre, and the sardina. The two last descend into the lake with the streams that flow into it. The guavina, of which I made a drawing on the spot, is 20 inches long and 3.5 broad. It is perhaps a new species of the genus erythrina of Gronovius. It has large silvery scales edged with green. This fish is extremely voracious, and destroys other kinds. The fishermen assured us that a small crocodile, the bava,* which often approached us when we were bathing, contributes also to the destruction of the fish. (* The bava, or bavilla, is very common at Bordones, near Cumana. See volume 1. The name of bava, baveuse, has misled M. Depons; he takes this reptile for a fish of our seas, the Blennius pholis. Voyage a la Terre Ferme. The Blennius pholis, smooth blenny, is called by the French baveuse (slaverer), in Spanish, baba.) We never could succeed in procuring this reptile so as to examine it closely: it generally attains only three or four feet in length. It is said to be very harmless; its habits however, as well as its form, much resemble those of the alligator (Crocodilus acutus). It swims in such a manner as to show only the point of its snout, and the extremity of its tail; and places itself at mid-day on the bare beach. It is certainly neither a monitor (the real monitors living only in the old continent,) nor the sauvegarde of Seba (Lacerta teguixin,) which dives and does not swim. It is somewhat remarkable that the lake of Valencia, and the whole system of small rivers flowing into it, have no large alligators, though this dangerous animal abounds a few leagues off in the streams which flow either into the Apure or the Orinoco, or immediately into the Caribbean Sea between Porto Cabello and La Guayra.

In the islands that rise like bastions in the midst of the waters, and wherever the rocky bottom of the lake is visible, I recognised a uniform direction in the strata of gneiss. This direction is nearly that of the chains of mountains on the north and south of the lake. In the hills of Cabo Blanco there are found among the gneiss, angular


Equinoctial Regions of America V2 - 4/97

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