In the province of Caracas the light green of the Tahitian sugar-cane forms a beautiful contrast with the dark shade of the cacao plantations. Few tropical trees have so thick a foliage as the Theobroma Cacao. This noble tree thrives best in hot and humid valleys. Extreme fertility of soil and insalubrity of atmosphere are as inseparably connected in South America as in Southern Asia. Nay, it has even been observed that in proportion as the cultivation of the land increases, and the woods are removed, the soil and the climate become less humid, and the cacao plantations thrive less luxuriantly. But while they diminish in numbers in the province of Caracas, they spread rapidly in the eastern provinces of New Barcelona and Cumana, more especially in the humid woody region lying between Cariaco and the Golfo Triste.
[2]. p. [1]—“The natives term this phenomenon ‘banks.’”
The Llanos of Caracas are covered with a widely-extended formation of ancient conglomerate. On passing from the valleys of Aragua over the most southern range of the coast chain of Guigue and Villa de Cura, descending towards Parapara, the traveller meets successively with strata of gneiss and micaceous schist, a probably Silurian transition rock of argillaceous schist and black limestone; serpentine and greenstone in detached spheroidal masses; and lastly, on the margin of the great plain, small elevations of augitic amygdaloid and porphyritic schist. These hills between Parapara and Ortiz appear to me to be produced by volcanic eruptions on the old sea-shore of the Llanos. Further to the north, rise the far-famed cavernous and grotesquely-shaped elevations known as the Morros de San Juan, which form a species of devil’s dyke, the grain of which is crystalline, like upheaved dolomite. They are, therefore, to be regarded rather as portions of the shore than as islands in the ancient gulf. I consider the Llanos to have been a gulf, for when their inconsiderable elevation above the present sea level, the adaptation of their form to the rotation current, running from east to west, and the lowness of the eastern shore between the mouth of the Orinoco and the Essequibo are taken into account, it can scarcely be doubted that the sea once overflowed the whole of this basin between the coast chain and the Sierra de la Parime, extending westward to the mountains of Merida and Pamplona (in the same manner as it probably passed through the plains of Lombardy to the Cottian and Pennine Alps). Moreover, the inclination or line of strike of these Llanos is directed from west to east. Their elevation at Calabozo, a distance of 100 geographical (400 English) miles from the sea, scarcely amounts to 30 toises, or 192 English feet; consequently 15 toises (96 English feet) less than the elevation of Pavia, and 45 toises (288 English feet) less than that of Milan in the plain of Lombardy between the Swiss Lepontine Alps and the Ligurian Apennines. This conformation of the land reminds us of Claudian’s expression, “curvata tumore parvo planities.” The surface of the Llanos is so perfectly horizontal that in many parts over an area of some 480 English square miles, not a single point appears elevated one foot above the surrounding level. When it is further borne in mind that there is a total absence of all shrubs, and that in some parts, as in the Mesa de Pavones, there is not even a solitary palm-tree to be seen, it may easily be supposed that this sea-like and dreary plain presents a most singular aspect. Far as the eye can range, it scarcely rests on any object elevated many inches above the general level. If the boundary of the horizon did not continually present an undefined flickering and undulating outline, owing to the condition of the lower strata of air, and the refraction of light, solar elevations might be determined by the sextant above the margin of the plain as above the horizon of the sea. This perfect flatness of the ancient sea-bottom renders the banks even more striking. They are composed of broken floetz-strata, which rise abruptly about two or three feet above the surrounding level, and extend uniformly over a length of from 10 to 12 geographical (i.e., 40 to 48 English) miles. It is here that the small rivers of the Steppe take their origin.
On our return from the Rio Negro, we frequently met with traces of landslips in passing over the Llanos of Barcelona. We here found in the place of elevated banks, isolated strata of gypsum lying from 3 to 4 toises, or 19 to 25 English feet, below the contiguous rock. Further westward, near the confluence of the River Caura and the Orinoco, a large tract of thickly grown forest land to the east of the Mission of San Pedro de Alcantara, fell in after an earthquake in the year 1790. A lake was immediately formed in the plain, which measured upwards of 300 toises (1919 feet) in diameter. The lofty trees, as the Desmanthus, Hymenæa, and Malpighia, retained their verdure and foliage for a long time after their submersion.
[3]. p. [2]—“A shoreless ocean seems spread before us.”
The distant aspect of the Steppe is the more striking when the traveller emerges from dense forests, where his eye has been familiarised to a limited prospect and luxuriant natural scenery. I shall ever retain an indelible impression of the effect produced on my mind by the Llanos, when, on our return from the Upper Orinoco, they first broke on our view from a distant mountain, opposite the mouth of the Rio Apure, near the Hato del Capuchino. The last rays of the setting sun illumined the Steppe, which seemed to swell before us like some vast hemisphere, while the rising stars were refracted by the lower stratum of the atmosphere. When the plain has been excessively heated by the vertical rays of the sun, the evolution of the radiating heat, the ascent of currents of air, and the contact of atmospheric strata of unequal density, continue throughout the night.
[4]. p. [2]—“The naked stony crust.”
The deserts of Africa and Asia acquire a peculiar character from the frequent occurrence of immense tracts of land, covered by one flat uniform surface of naked rock. In the Scha-mo, which separates Mongolia and the mountain chain of Ulangom and Malakha-Oola from the north-west part of China, such rocky banks are termed Tsy. In the woody plains of the Orinoco they are found to be surrounded with the most luxuriant vegetation.[[J]] In the midst of these flat, tabular masses of granite and syenite, several thousands of feet in diameter, presenting merely a few scattered lichens, we find in the forests, or on their margins, little islands of light soil, covered with low and ever-flowering plants, having the appearance of small gardens. The monks settled on the Upper Orinoco, singularly enough regard the whole of these horizontal naked stony plains, when extending over a considerable area, as conducive to fevers and other diseases. Many of the villages belonging to the mission have been transferred to other spots on account of the general prevalence of this opinion. Do these stony flats (laxas) act chemically on the atmosphere or influence it only by means of a greater radiation of heat?
[5]. p. [2]—“Compared with the Llanos and Pampas of South America, or even with the Prairies on the Missouri.”
Our physical and geognostic knowledge of the western mountain region of North America has recently been enriched by the acquisition of many accurate data yielded by the admirable labours of the enterprising traveller Major Long, and his companion Edwin James, but more especially by the comprehensive investigations of Captain Frémont. The knowledge thus established clearly corroborates the accuracy of the different facts which in my work on New Spain I could merely advance as hypothetical conjectures regarding the northern plains and mountains of America. In natural history, as well as in historical research, facts remain isolated until by long-continued investigation they are brought into connection with each other.