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.
The Mantiqueira-Espinhago chain shuts out the streams flowing directly east to the Atlantic, and the boundary ranges on the west shut out the streams that flow into the Tocantins, though their sources are on the actual threshold of the state.
A relief map of Brazil shows two very irregular divisions of surface: the great river basins, or plains, of the Amazon-Tocantins and La Plata, which are practically connected by low elevations in Bolivia, and a huge, shapeless mass of highlands filling the eastern projection of the continent and extending southward to the plains of Rio Grande do Sul and westward to the Bolivian frontier.
The two great river basins of the Amazon-Tocantins and La Plata comprise within themselves, approximately, three-fifths of the total area of Brazil.
The second system - the Central or Goyana - consists of two distinct chains of mountains converging toward the north in the elevated chapadao between the Tocantins and Sao Francisco basins.
And Tocantins-Araguaya basins.
The Sao Francisco chapadao, which has a general elevation of about 2600 ft., covers the greater part of the states of Minas Geraes and Bahia, and a small part of western Pernambuco, and might also be considered continuous with those of the Parnahyba and Tocantins-Araguaya basins.
It includes the river basins of the Tocantins-Araguaya, Xingu, Tapajos, and the eastern tributaries of the Guapore-Madeira.
If the Tocantins-Araguaya basin is included in the hydrographic system, the greater part of Goyaz and a small part of Maranhao should be added to this drainage area.
The Tocantins is sometimes treated as a tributary of the Amazon because its outlet, called the Rio Para, is connected with that great river by a number of inland channels.
As the outlet of the Tocantins is so near to that of the Amazon, and their lower valleys are conterminous, it is convenient to treat them as parts of the same hydrographic basin.
The lower river valleys of the Tocantins-Araguaya, Xingu, Tapajos and Paraguay are essentially tropical, their climate being hot and humid like that of the Amazon.
A part of the western boundary is formed by the Tocantins, and another part by the Gurupy, which separates the state from Para.
ARAGUAYA, ARAGUAY or Araguia, a river of Brazil and principal affluent of the Tocantins, rising in the Serra do Cayap6, where it is known as the Rio Grande, and flowing in a north by east direction to a junction with the Tocantins at Sao Joao do Araguaya, or Sao Joao das Duas Barras.
See Coudreau's Voyage au Tocantins-Araguaya (Paris, 1897).
Starting from Path, he penetrated to the banks of the Tocantins, making numerous converts to Christianity and civilization among the most savage tribes; but after two years of unceasing labour, during which every difficulty was placed in his way by the colonial authorities, he saw that the Indians must be withdrawn from the jurisdiction of the governors, to prevent their exploitation, and placed under the control of the members of a single religious society.
M., if the Tocantins be included in its basin.
The Tocantins is not really a branch of the Amazon, although usually so considered.
Above its junction with the Tocantins, it saws its way across a rocky dyke for 12 m.
The tributaries of the Tocantins, called the Maranhao and Parana-tinga, collect an immense volume of water from the highlands which surround them, especially on the south and south-east.
Between the latter and the confluence with the Araguay, the Tocantins is occasionally obstructed by rocky barriers which cross it almost at a right angle.
The flat, broad valleys, composed of sand and clay, of both the Tocantins and its Araguay branch are overlooked by steep bluffs.
Around the estuary of the Tocantins the great plateau has disappeared, to give place to a part of the forest-covered, half submerged alluvial plain, which extends far to the north-east and west.
The Xingu, the next large river west of the Tocantins, is a true tributary of the Amazon.
Of the Tocantins basin.