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granitic and solitary mounds, all resembling 

 those, which are found in the shape of islands 

 and shoals in the present bed of the river. I 

 was struck with this analogy of form, on com 

 paring the rocks Keri and Oco, situate in the 

 deserted bed of the river, west of Maypures, 

 with the islets of Ouivitari and Caminitamini, 

 which rise like old castles amid the cataracts to 

 the east of the mission. The geological aspect 

 of these scenes, the insulary form of the ele- 

 vations farthest from the present shore of the 

 Oroonoko, the cavities which the waves appear 

 to have hollowed in the rock Oco, and which 

 are precisely of the same level (25 or 30 toises 

 high) as the excavations perceived opposite to 

 them in the isle of Ouivitari ; these united 

 appearances prove, that the whole of this bay, 

 now dry, was formerly covered by the waters. 

 Those waters probably formed a lake, the north- 

 ern dike preventing their running out : but, 

 when this dike was broken down, the savannah, 

 that surrounds the mission, appeared at first like 

 a very low island, bounded by two arms of the 

 same river. It may be supposed, that the Oroo- 

 noko continued for some time to fill the ravin, 

 which we shall call the valley of Keri, because 

 it contains the rock of this name ; and that the 

 waters retired wholly toward the eastern chain, 

 leaving dry the western arm of the river, only 

 as they gradually diminished. Coloured stripes, 



