SANDSTONE OE THE ILANOS 
889 
fi7ie quartz; I saw no fragments of porphyry or limestone. 
Tliose immense beds of sandstone that cover the Llanos of 
the Lower Orinoco and the Amazon, well deserve the atten- 
tion of travellers. In 'Sppearance tliey approximate to the 
pudding-stones of the molassiis sti-atum, in which calcsireous 
vestiges are also often wanting, as at Sehottwyl and Bies- 
hach in Switzerland; but they appeared to me bv 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 Itivcro found 
along the Cordilleras of New Grenada, bordering the steppes 
■on the west. Does the want of fragments of granite, gneiss, 
and porphvryq and the frequency of petrified wood,* some- 
times dicotyledonous, indicate that those sandstones belong 
to the more recent formations which till the plains between 
the Cordillera of the Tarime and the coast Cordillera, as the 
molassus of Switzerland fills the space between the J ura 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 Waldgebirgc. M. Boussingault, 
who passed through a part of the steppes ot A^ene/mela long 
after me, is of opinion that the sandstone of the Llanos ot 
San Carlos, that of the valley of Sail Antonio de Cucuta, 
and the table-lands of Barqiiisimeto, Tocuyo, hlerida, and 
Tru.\iilo, belong to a formation of old red sandstone, or 
coal. There is in fact real coal near Carache, south-west ot 
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 virgilioYdcs (See Nova Gen. et Spec. Plant, yol. ui, p- 3/ / }, and 
to the Chttvarro boto, Khopala complicata. It is believed, m Venezuela 
as in Egypt, that petrified wood is formed in our times. 1 fonnd this 
dicotyledonous jietrified wood only at the ^ ® T* kur <;om» 
inclosed in the sandstone of tlie Llanos. M. Caillaud ma e 
observation on going to the Oasis of Siwa. ? 
feet long, inclosed in the red sandstone of Kifhauser C-'? ? 
according to the recent researches of Von Bucb, divided into joints, and 
are certainly monocotyledonous. 
