NOTES ON THE REGION ABOUT CAICARA, VENEZUELA 243 



and by the writer overlying the gneisses on the banks of the Orinoco. 

 As long as the deposit is under water or is still charged with water 

 after the streams have fallen during the dry season, it is very 

 pliable; but as soon as it becomes dehydrated, it turns extremely 

 hard and takes on the aspect of a clay ironstone. It has been 



Gneisses. — Level of Orinoco 



Fig. 2 



called "Laterite," and likened to the German "Zellinger Braun- 

 eisenstein." The only true laterite portions form the upper part 

 of the clayey mass or are segregated from this. The clays are in 

 many places marbled by a more or less intense red. The deposit 

 directly and unconformably overlies the gneissic or granitic bed 

 rock. The deposit is not continuous and is frequently replaced 

 by a conglomerate, cemented by iron oxide (see Fig. 2) . It occurs 

 inland as well as along the Orinoco. 



Clays, loams, and sands 



^ Laterite segregation 



Level of Orinoco 



Fig. 



2. The Upper Llanos deposits. — The Upper Llanos deposits 

 which, as a rule, unconformably overlie the "laterite," wherever 

 they have not been removed by erosion, may be said to consist 

 of the following three members: (1) A whitish or yellowish clay 

 which exhibits yellowish-brown cell structure, rich in iron; (2) 

 loams of various nature; (3) sands of different fineness and color. 



Their interrelation changes with the locality and so do their 

 respective horizons. They constitute the upper portions of the 

 islands, as well as the upper terraces at an elevation of 50 feet, 

 approximately, above the average level of the lower terraces, and 



