The form of the surface of this part of the globe reminds one of Claudian’s expression, “curvata tumore parvo planities.” The horizontality of the Llanos is so perfect that in many portions of them no part of an area of more than 480 square miles appears to be a foot higher than the rest. If, in addition to this, we imagine to ourselves the absence of all bushes, and even in the Mesa de Pavones the absence of any isolated palm-trees, it will afford some idea of the singular aspect of this sea-like desert plain. As far as the eye can reach, it can hardly rest on a single object a few inches high. If it were not that the state of the lowest strata of the atmosphere, and the consequent changes of refraction, render the horizon continually indeterminate and undulating, altitudes of the sun might be taken with the sextant from the margin of the plain as well as from the horizon at sea. This great horizontality of the former sea bottom makes the “banks” more striking. They are broken strata which rise abruptly from two to three feet above the surrounding rock, and extend uniformly over a length of from 40 to 48 English geographical miles. The small streams of the Steppes take their rise on these banks. In passing through the Llanos of Barcelona, on our return from the Rio Negro, we found frequent traces of earthquakes. Instead of the banks standing _higher_ than the surrounding rock, we found here solitary strata of gypsum from 3 to 4 toises (19 to 25 English feet) _lower_. Farther to the west, near the junction of the Caura with the Orinoco, and to the east of the mission of S. Pedro de Alcantara, an extensive tract of dense forest sank down in an earthquake in 1790, and a lake was formed of more than 300 toises (1918 English feet) diameter. The tall trees (Desmanthus, Hymenæas, and Malpighias) long retained their foliage and verdure under the water. [3] p. 2.--“_We seem to see before us a shoreless ocean._” The prospect of the distant Steppe is still more striking, when the spectator has been long accustomed in the dense forests both to a very restricted field of view, and to the aspect of a rich and highly luxuriant vegetation. Ineffaceable is the impression which I received on our return from the Upper Orinoco, when, from the Hato del Capuchino, on a mountain opposite to the mouth of the Rio Apure, we first saw again the distant Steppe. The sun had just set; the Steppe appeared to rise like a hemisphere; and the light of the rising stars was refracted in the lowest stratum of air. The excessive heating of the plain by the vertical rays of the sun causes the variations of refraction,--occasioned by the effects of radiation, of the ascending current, and of the contact of strata of air of unequal density,--to continue through the entire night. [4] p. 2.--“_The naked stony crust._”