619 



cemented by a ferruginous, olive-brown clay. 

 (Vol. iv, p. 384, 385.) We there find fragments 

 of wood, in great part monocotyledon, and 

 masses of brown iron. Some layers (Mesa de 

 Paja) present grains of very fine quartz ; I saw 

 no fragments of porphyry, or limestone. Those 

 immense beds of sandstone that cover the 

 Llanos of the Lower Oroonoko and the Ama- 

 zon, merit the greatest attention of travellers. 

 By their aspect they draw near the nagelfluhes 

 or pudding-stones of the inolassus soil, in which 

 calcareous vestiges are also often wanting, 

 (Schottwyl and Diesbach, in Switzerland*); 

 but they appeared to me by their position to 

 have rather a relation to red sandstone. They 

 can no where be confounded with the grau- 

 wackes (fragmentary transition-rocks) which 

 MM. Boussingault and Rivero sfx found along 



427). Layers of very fine rounded gneiss of quartz are in- 

 closed in the tote liegende of Thuringia, (Freiesleben, Vol. iv, 

 p. 97) and in Upper Silesia (Ocyhaussen, Besch. von Ober- 

 schlesien, p. 119). 



* Meisner, Annalen der al/gem. schweiz. Geseliscfiqft, P. I # 

 p. 49. 



f Those travellers not only levelled their route by means 

 of the barometer, but also determined the position of a great 

 number of points by meridian observations of the Sun and 

 Canopus, and by the use of a time-keeper* 1 shall here 

 transcribe some latitudes that are very uncertain on our 

 maps : Maracay, 10° 15' 58"; San Carlos, 9<> 40' 10"; Bar- 

 quisimeto, 9° 54' 35"; Tocuyo, 9° 15' 51 "5 Truxillo, 



