On the Ancient River-deposit of the Amazon

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Abstract
It is my intention to endeavour to describe in this paper the mode of occurrence, deposition, and general characters of a vast deposit of ancient alluvial matter which forms a great portion of the valley of the Amazon, and to deduce therefrom some facts regarding the deposition of detrital matters by this great river. In ascending the Amazon, one cannot fail to be struck by the appearance of lines of cliffs at long intervals apart⁁ first on one hand, and then upon the other⁁which, rendered conspicuous by their bright colouring, form a pleasing contrast to the monotonous line of low greyish.clay river-sides which elsewhere meets the eye. In fact, they on the one hand, and a great plain of recent alluvium on the other, when the river is flowing on one side or the other of its present valley, are the chief features in the physical geography of the Amazon and its tributaries. The accompanying diagrammatic section (fig. 1) will explain the relative position of the two. Exceptions to the above-described conditions are only seen on the Lower Amazon at Almeyrin and Montealegré (where views of some picturesque scenery are obtained, produced by sandstone mountains of doubtful Triassic age), and at Santarem, on the Tapajos river, on the Trombettas river, at Parintins, Juruty, and Faro (where there are table-lands rising, in some instances, to a height of 460 feet above the general level, which are composed of beds of friable sandstone and clay, of grey, white, and reddish colours). The

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