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- Equinoctial Regions of America V2 - 5/97 -

masses of opaque quartz, slightly translucid on the edges, and varying from grey to deep black. This quartz passes sometimes into hornstein, and sometimes into kieselschiefer (schistose jasper). I do not think it constitutes a vein. The waters of the lake* decompose the gneiss by erosion in a very extraordinary manner. (* The water of the lake is not salt, as is asserted at Caracas. It may be drunk without being filtered. On evaporation it leaves a very small residuum of carbonate of lime, and perhaps a little nitrate of potash. It is surprising that an inland lake should not be richer in alkaline and earthy salts, acquired from the neighbouring soils. I have found parts of it porous, almost cellular, and split in the form of cauliflowers, fixed on gneiss perfectly compact. Perhaps the action ceases with the movement of the waves, and the alternate contact of air and water.

The island of Chamberg is remarkable for its height. It is a rock of gneiss, with two summits in the form of a saddle, and raised two hundred feet above the surface of the water. The slope of this rock is barren, and affords only nourishment for a few plants of clusia with large white flowers. But the view of the lake and of the richly cultivated neighbouring valleys is beautiful, and their aspect is wonderful after sunset, when thousands of aquatic birds, herons, flamingoes, and wild ducks cross the lake to roost in the islands, and the broad zone of mountains which surrounds the horizon is covered with fire. The inhabitants, as we have already mentioned, burn the meadows in order to produce fresher and finer grass. Gramineous plants abound, especially at the summit of the chain; and those vast conflagrations extend sometimes the length of a thousand toises, and appear like streams of lava overflowing the ridge of the mountains. When reposing on the banks of the lake to enjoy the soft freshness of the air in one of those beautiful evenings peculiar to the tropics, it is delightful to contemplate in the waves as they beat the shore, the reflection of the red fires that illumine the horizon.

Among the plants which grow on the rocky islands of the lake of Valencia, many have been believed to be peculiar to those spots, because till now they have not been discovered elsewhere. Such are the papaw-trees of the lake; and the tomato* of the island of Cura. (* The tomatoes are cultivated, as well as the papaw-tree of the lake, in the Botanical Garden of Berlin, to which I had sent some seeds.) The latter differs from our Solanum lycopersicum; the fruit is round and small, but has a fine flavour; it is now cultivated at La Victoria, at Nueva Valencia, and everywhere in the valleys of Aragua. The papaw-tree of the lake (papaya de la laguna) abounds also in the island of Cura and at Cabo Blanco; its trunk shoots higher than that of the common papaw (Carica papaya), but its fruit is only half as large, perfectly spherical, without projecting ribs, and four or five inches in diameter. When cut open it is found quite filled with seeds, and without those hollow places which occur constantly in the common papaw. The taste of this fruit, of which I have often eaten, is extremely sweet.* (* The people of the country attribute to it an astringent quality, and call it tapaculo.) I know not whether it be a variety of the Carica microcarpa, described by Jacquin.

The environs of the lake are insalubrious only in times of great drought, when the waters in their retreat leave a muddy sediment exposed to the rays of the sun. The banks, shaded by tufts of Coccoloba barbadensis, and decorated with fine liliaceous plants,* (* Pancratium undulatum, Amaryllis nervosa.) remind us, by the appearance of the aquatic vegetation, of the marshy shores of our lakes in Europe. We find there, pondweed (potamogeton), chara, and cats'-tail three feet high, which it is difficult not to confound with the Typha angustifolia of our marshes. It is only after a careful examination, that we recognise each of these plants for distinct species,* (* Potamogeton tenuifolium, Chara compressa, Typha tenuifolia.) peculiar to the new continent. How many plants of the straits of Magellan, of Chile, and the Cordilleras of Quito have formerly been confounded with the productions of the northern temperate zone, owing to their analogy in form and appearance.

The inhabitants of the valleys of Aragua often inquire why the southern shore of the lake, particularly the south-west part towards los Aguacotis, is generally more shaded, and exhibits fresher verdure than the northern side. We saw, in the month of February, many trees stripped of their foliage, near the Hacienda de Cura, at Mocundo, and at Guacara; while to the south-east of Valencia everything presaged the approach of the rains. I believe that in the early part of the year, when the sun has southern declination, the hills around Valencia, Guacara, and Cura are scorched by the heat of the solar rays, while the southern shore receives, along with the breeze when it enters the valley by the Abra de Porto Cabello, an atmosphere which has crossed the lake, and is loaded with aqueous vapour. On this southern shore, near Guaruto, are situated the finest plantations of tobacco in the whole province.

Among the rivers flowing into the lake of Valencia some owe their origin to thermal springs, and deserve particular attention. These springs gush out at three points of the granitic Cordillera of the coast; near Onoto, between Turmero and Maracay; near Mariara, north-east of the Hacienda de Cura; and near Las Trincheras, on the road from Nueva Valencia to Porto Cabello. I could examine with care only the physical and geological relations of the thermal waters of Mariara and Las Trincheras. In going up the small river Cura towards its source, the mountains of Mariara are seen advancing into the plain in the form of a vast amphitheatre, composed of perpendicular rocks, crowned by peaks with rugged summits. The central point of the amphitheatre bears the strange name of the Devil's Nook (Rincon del Diablo). The range stretching to the east is called El Chaparro; that to the west, Las Viruelas. These ruin-like rocks command the plain; they are composed of a coarse-grained granite, nearly porphyritic, the yellowish white feldspar crystals of which are more than an inch and a half long. Mica is rare in them, and is of a fine silvery lustre. Nothing can be more picturesque and solemn than the aspect of this group of mountains, half covered with vegetation. The Peak of Calavera, which unites the Rincon del Diablo to the Chaparro, is visible from afar. In it the granite is separated by perpendicular fissures into prismatic masses. It would seem as if the primitive rock were crowned with columns of basalt. In the rainy season, a considerable sheet of water rushes down like a cascade from these cliffs. The mountains connected on the east with the Rincon del Diablo, are much less lofty, and contain, like the promontory of La Cabrera, and the little detached hills in the plain, gneiss and mica-slate, including garnets.

In these lower mountains, two or three miles north-east of Mariara, we find the ravine of hot waters called Quebrada de Aguas Calientes. This ravine, running north-west 75 degrees, contains several small basins. Of these the two uppermost, which have no communication with each other, are only eight inches in diameter; the three lower, from two to three feet. Their depth varies from three to fifteen inches. The temperature of these different funnels (pozos) is from 56 to 59 degrees; and what is remarkable, the lower funnels are hotter than the upper, though the difference of the level is only seven or eight inches. The hot waters, collected together, form a little rivulet, called the Rio de Aguas Calientes, which, thirty feet lower, has a temperature of only 48 degrees. In seasons of great drought, the time at which we visited the ravine, the whole body of the thermal waters forms a section of only twenty-six square inches. This is considerably augmented in the rainy season; the rivulet is then transformed into a torrent, and its heat diminishes for it appears that the hot springs themselves are subject only to imperceptible variations. All these springs are slightly impregnated with sulphuretted hydrogen gas. The fetid smell, peculiar to this gas, can be perceived only by approaching very near the springs. In one of these wells only, the temperature of which is 56.2 degrees, bubbles of air are evolved at nearly regular intervals of two or three minutes. I observed that these bubbles constantly rose from the same points, which are four in number; and that it was not possible to change the places from which the gas is emitted, by stirring the bottom of the basin with a stick. These places correspond no doubt to holes or fissures on the gneiss; and indeed when the bubbles rise from one of the apertures, the emission of gas follows instantly from the other three. I could not succeed in inflaming the small quantities of gas that rise above the thermal waters, or those I collected in a glass phial held over the springs, an operation that excited in me a nausea, caused less by the smell of the gas, than by the excessive heat prevailing in this ravine. Is this sulphuretted hydrogen mixed with a great proportion of carbonic acid or atmospheric air? I am doubtful of the first of these mixtures, though so common in thermal waters; for example at Aix la Chapelle, Enghien, and Bareges. The gas collected in the tube of Fontana's eudiometer had been shaken for a long time with water. The small basins are covered with a light film of sulphur, deposited by the sulphuretted hydrogen in its slow combustion in contact with the atmospheric oxygen. A few plants near the springs were encrusted with sulphur. This deposit is scarcely visible when the water of Mariara is suffered to cool in an open vessel; no doubt because the quantity of disengaged gas is very small, and is not renewed. The water, when cold, gives no precipitate with a solution of nitrate of copper; it is destitute of flavour, and very drinkable. If it contain any saline substances, for example, the sulphates of soda or magnesia, their quantities must be very insignificant. Being almost destitute of chemical tests,* (* A small case, containing acetate of lead, nitrate of silver, alcohol, prussiate of potash, etc., had been left by mistake at Cumana. I evaporated some of the water of Mariara, and it yielded only a very small residuum, which, digested with nitric acid, appeared to contain only a little silica and extractive vegetable matter.) we contented ourselves with filling at the spring two bottles, which were sent, along with the nourishing milk of the tree called palo de vaca, to MM. Fourcroy and Vauquelin, by the way of Porto Cabello and the Havannah. This purity in hot waters issuing immediately from granite mountains is in Europe, as well as in the New Continent, a most curious phenomenon.* (* Warm springs equally pure are found issuing from the granites of Portugal, and those of Cantal. In Italy, the Pisciarelli of the lake Agnano have a temperature equal to 93 degrees. Are these pure waters produced by condensed vapours?) How can we explain the origin of the sulphuretted hydrogen? It cannot proceed from the decomposition of sulphurets of iron, or pyritic strata. Is it owing to sulphurets of calcium, of magnesium, or other earthy metalloids, contained in the interior of our planet, under its rocky and oxidated crust?

In the ravine of the hot waters of Mariara, amidst little funnels, the temperature of which rises from 56 to 59 degrees, two species of aquatic plants vegetate; the one is membranaceous, and contains bubbles of air; the other has parallel fibres. The first much resembles the Ulva labyrinthiformis of Vandelli, which the thermal waters of Europe furnish. At the island of Amsterdam, tufts of lycopodium and marchantia have been seen in places where the heat of the soil was far greater: such is the effect of an habitual stimulus on the organs of plants. The waters of Mariara contain no aquatic insects. Frogs are found in them, which, being probably chased by serpents, have leaped into the funnels, and there perished.

South of the ravine, in the plain extending towards the shore of the lake, another sulphureous spring gushes out, less hot and less impregnated with gas. The crevice whence this water issues is six toises higher than the funnel just described. The thermometer did not rise in the crevice above 42 degrees. The water is collected in a basin surrounded by large trees; it is nearly circular, from fifteen to eighteen feet diameter, and three feet deep. The slaves throw themselves into this bath at the end of the day, when covered with

Equinoctial Regions of America V2 - 5/97

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