The outline of the state is that of a roughly-shaped wedge with the thin edge extending northward between and up to the junction of the rivers Araguaya and Upper Tocantins, and its length is nearly 15° of latitude.
By the deeply eroded valleys of the Araguaya and Upper Tocantins rivers and their tributaries.
The general slope of the plateau is toward the N., and the drainage of the state is chiefly through the above-named rivers - the principal tributaries of the Araguaya being the Grande and Vermelho, and of the Upper Tocantins, the Manoel Alves Grande, Somno, Paranan and Maranhao.
Although the northern and southern extremities of Goyaz lie within two great river systems - the Tocantins and Parana - the upper courses of which are navigable, both of them are obstructed by falls.
On the western frontier a northern extension of the great central chain of Goyaz forms the water-parting between the drainage basins of the Sao Francisco and Tocantins, and is known at different points as the Serra do Paranan, Serra de Sao Domingos and Serra das Divisoes.
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