It is the central fluvial artery of Brazil, running from south to north for a distance of about 150o m.
Originally conquered by the fluvial deposits from the sea, it now stretches out as a vast dead level, in which the rivers find their velocity checked, and their current no longer able to carry along the silt which they have brought down from northern India.
But the relief of the tableland has been wholly changed by fluvial action.
These consisted of two piers forming a seaward prolongation of the fluvial channel, begun in 1858 and completed in 1861.
Although essentially a fluvial district, it does not possess any river navigable throughout the year by boats of 4 tons burden.
Along the whole northern rim of Bosnia, as also in the fluvial and Karst valleys (poljes), are found diluvial and alluvial formations, interrupted at one place by an isolated granite layer.
The careful study of these fluvial formations is likely to throw much light on the history of the deformative movements and changes in topography in the United States during the late stages of geological history.
Ruthenus), the tench, the gudgeon and other fluvial species also appear in immense numbers.
This is one of the most important fluvial systems of Brazil, but its economic value is impaired by the great waterfalls of Guayra, or Sete Quedas, and Uribu-punga, and by the rapids and waterfalls in the majority of its affluents near their junction with the main stream.