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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 whicfr 

 are precisely on the same level (25 or 30 

 toises high) as the excavations perceived oppo- 

 site to them in the isle of Ouivitari ; these unit- 

 ed appearances prove, that the whole of this 

 bay, now dry, was formerly covered by the 

 waters. Those waters probably formed a lake, 

 the northern dike preventing their running out : 

 but, when this dike was broken down, the sa- 

 vannah, that surrounds the mission, appeared at 

 first like a very low island, bounded by two arms j 

 of the same river. It may be supposed, that the 

 Oroonoko continued for some time to fill the ra- 

 vin, 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, 



