178 CATARACTS OF THE ORINOCO. 



extends between the two chains of hills. The Jesuits have built 

 upon it a small church formed of the trunks of palm trees. 



The geological aspect of the district, the shapes of the rocks of 

 Keri and Oco, which have so much the character of islands, the 

 water-worn hollows in the first named of these rocks, situated at 

 exactly the same height as the cavities in the opposite island of 

 Uivitari, all testify that the Orinoco once filled the whole of this 

 now dry gulf or bay. Probably the waters formed a wide lake as 

 long as the northern dike was able to withstand their pressure. 

 When it gate way, the prairie now inhabited by the Guareke In- 

 dians must have been the first part which appeared above the 

 waters; which may subsequently, perhaps, have long continued to 

 surround the rocks of Keri and Oco, which, rising like mountain 

 fortresses from the ancient bed of the river, present a picturesque 

 aspect. As the waters gradually diminished, they withdrew alto- 

 gether to the foot of the eastern hills, where the river now flows. 



This conjecture is confirmed by several circumstances. The 

 Orinoco, like the Nile near Philse and Syene, has the property of 

 imparting a black color to the reddish-white masses of granite which 

 it has bathed for thousands of years. As far as the waters reach, 

 one may remark on the rocky shore the leaden-colored coating 

 described at page 155 : its presence, and the hollows before men- 

 tioned, mark the ancient height of the waters of the Orinoco. 



In the rock of Keri, in the islands of the Cataracts, in the gneiss 

 hills of Cumadaminari above the Island of Tomo, and lastly at the 

 mouth of the Jao, we trace these black-colored hollows at elevations 

 of 150 to 180 (160 to 192 English) feet above the present height 

 of the river. Their existence teaches us a fact of which we may 

 also observe indications in the river beds of Europe : viz., that the 

 streams whose magnitude now excites our astonishment are only 

 the feeble remains of the immense masses of water belonging to an 

 earlier age of the world. 



These simple remarks and inferences have not escaped even the 

 rude natives of Guiana. The Indians everywhere called our atten- 

 tion to the traces of the former height of the waters. There is, in a 

 grassy plain near Uruana, an isolated granite rock, on which, accord- 

 ing to the report of trustworthy witnesses, there are at a height of 



