SANDSTONE OF THE LLANOS 889 



fine quartz ; I saw no fragments of porphyry or limestone. 

 Those immense beds of sandstone that cover the Llanos of 

 the Lower Orinoco and the Amazon, well deserve the atten- 

 tion of travellers. In appearance they approximate to the 

 pudding-stones of the molassus stratum, in which calcareous 

 vestiges are also often wanting, as at Schottwyl and Dies- 

 bach in Switzerland ; but they appeared to me by their posi- 

 tion to have more relation to red sandstone. Nowhere can 

 they be confounded with the grauwackes (fragmentary tran- 

 sition-rocks) which MM. Boussingault and Eivero found 

 along the Cordilleras of New Grenada, bordering the steppes 

 on the west. Does the want of fragments of granite, gneiss, 

 and porphyry, and the frequency of petrified wood,* some- 

 times dicotyledonous, indicate that those sandstones belong 

 to the more recent formations which fill the plains between 

 the Cordillera of the Parime and the coast Cordillera, as the 

 molassus of Switzerland fills the space between the Jura and 

 the Alps ? It is not easy, when several formations are not 

 perfectly developed, to determine the age of arenaceous rocks. 

 The most able geologists do not concur in opinion respecting 

 the sandstone of the Black Forest, and of the whole country 

 south-west of the Thuringer Waldgebirge. M. Boussingault, 

 who passed through a part of the steppes of Venezuela long 

 after me, is of opinion that the sandstone of the Llanos of 

 San Carlos, that of the valley of San Antonio de Cucuta, 

 and the table-lands of Barquisimeto, Tocuyo, Merida, and 

 Truxillo, belong to a formation of old red sandstone, or 

 coal. There is in fact real coal near Carache, south-west of 

 the Paramo de las Eosas. 



Before a part of the immense plains of America was 

 geologically examined, it might have been supposed that 



* The people of the country attribute those woods to the Alcornoco, 

 Bowdichia virgilioldes (See Nova Gen. et Spec. Plant, vol. iii, p. 377), and 

 to the Chaparro bovo, Rhopala coniplicata. It is believed, in Venezuela 

 as in Egypt, that petrified wood is formed in our times. I found this 

 dicotyledonous petrified wood only at the surface of the soil, and not 

 inclosed in the sandstone of the Llanos. M. Caillaud made the same 

 observation on going to the Oasis of Siwa. The trunks of trees, ninety 

 feet long, inclosed in the red sandstone of Kifhauser (in Saxony), are, 

 according to the recent researches of Von Buch, divided into joints, and 

 we certainly inonocotyledonoua. 



