28 VIETV'S OF NATURE. 



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 con- 

 fluence 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, Hymena?a, and Malpi- 

 ghia, retained their verdure and foliage for a long time after 

 their submersion. 



(3) p. 2 — Ci A shoreless ocean seems spread before z/s." 

 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 moutn of the 

 Ilio Apure, near the Hato del Capuchino. The last rays of 

 the setting sun illumined the Steppe, which seemed to swell 

 bofore 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 cha- 

 racter from the frequent occurrence of immense tracts of 

 land, covered by one flat uniform surface of naked rock. In 

 the Schamo, which separates Mongolia and the mountain 

 chain of Ulangom and Malakha-Oola from the north-west 



