ALTERATION
OF
THE
WATER-LEVEL.
297
t h e eastern bank, t h e Sanariapo, and on the western, t h e Cameji and the T o p a r o . O p p o s i t e the village o f M a y p u r e s , t h e mountains fall back in an arch, and, like a r o c k y coast, form a g u l f o p e n to the south-east. T h e irruption o f t h e river is effected b e t w e e n the m o u t h s o f the T o p a r o and the Sanariapo, at the western extremity o f this majestic amphitheatre. T h e waters o f t h e O r i n o c o n o w roll at t h e f o o t o f t h e eastern chain o f the mountains, and have r e c e d e d from t h e west, where, in a d e e p valley, the ancient shore is easily recognized. A savannah, scarcely raised thirty feet a b o v e the mean level o f the river, extends from this valley as far as the cataracts. There the small church o f M a y p u r e s has been constructed. I t is built o f trunks o f palm-trees, and is s u r r o u n d e d by seven o r eight huts. T h e dry valley, which runs in a straight line from south t o n o r t h , from the Cameji t o the T o p a r o , is filled with granitic and solitary m o u n d s , all resembling those found in the shape o f islands and shoals in the present b e d o f the river. I was s t r u c k with this analogy o f f o r m , o n c o m p a r i n g t h e r o c k s o f K e r i a n d O c o , situated in the deserted b e d o f t h e river, west o f M a y p u r e s , with t h e islets o f Ouivitari and Caminitamini, which rise like old castles amid the cataracts to the east o f the mission. T h e geological aspect o f these scenes, the insular form o f the elevations farthest from the present shore o f the O r i n o c o , the cavities which the waves appear t o have hollowed in t h e rock O c o , and which are precisely o n t h e same level ( t w e n t y five o r thirty toises h i g h ) as the excavations perceived o p p o site t o t h e m in t h e isle o f Ouivitari ; all these appearances p r o v e that the w h o l e o f this bay, n o w dry, was formerly covered by water. T h o s e waters probably formed a lake, the northern dike preventing their r u n n i n g out : but, when this dike was broken d o w n , the savannah that surrounds t h e mission appeared at first like a very low island, b o u n d e d by t w o arms o f the same river. It may be supposed that the O r i n o c o c o n t i n u e d for s o m e t i m e t o till the ravine, which We shall call the valley o f Keri, because it contains the rock o f that name ; and that t h e waters retired wholly t o w a r d the eastern chain, leaving dry the western arm o f the river, only as they gradually diminished. C o l o u r e d stripes, which n o d o u b t o w e their black tint t o the oxides o f iron and