Page:The naturalist on the River Amazons 1863 v1.djvu/23

 whilst in the Amazons the turbid flow of the mighty stream overpowers all tides, and produces a constant downward current. The colour of the water is different, that of the Pará being of a dingy orange-brown, whilst the Amazons has an ochreous or yellowish clay tint. The forests on their banks have a different aspect. On the Pará the infinitely diversified trees seem to rise directly out of the water; the forest frontage is covered with greenery, and wears a placid aspect, whilst the shores of the main Amazons are encumbered with fallen trunks, and are fringed with a belt of broad-leaved grasses. The difference is partly owing to the currents, which on the main river tear away the banks, and float out to sea an almost continuous line of dead trees and other debris of its shores.

We may, however, regard the combined mouths of the Pará and the Amazons with their archipelago of islands as forming one immense river delta, each side of which measures 180 miles—an area about equal to the southern half of England and Wales. In the middle of it lies the island of Marajo, which is as large as Sicily. The land is low and flat, but it does not consist entirely of alluvium or river deposit; in many parts the surface is rocky; rocks also form reefs in the middle of the Pará river. The immense volumes of fresh water which are poured through these broad embouchures, the united contributions of innumerable streams, fed by drenching tropical rains, prevent them from becoming salt-water estuaries. The water is only occasionally a little brackish near Pará, at high spring tides. Indeed, the fresh water tinges the sea along the shores of Guiana