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LAND AND RESOURCES Brazil is mostly highland. Its major physiographic regions include the Guiana Highlands, which are north of the Amazon River; the Amazon Basin itself; the Brazilian Highlands, which are south of the Amazon; and the Chaco. Brazil's highest mountain, Pico da Neblina (3,014 m/9,888 ft), is in the northwest of the country near the Venezuelan border. Similar geologic processes formed all of Brazil's highland regions. The deepest and oldest rocks are crystalline granites and quartzites. Over several million years these large blocks of land were upthrusted, dissected by erosion, and then inundated by the sea; during this period, sedimentary layers formed of varying thicknesses. Finally, another episode of uplift and erosion took place. Resistant diabase is responsible for the buttes and mesas common to Brazil's highlands. Uplift along the eastern margin produced the coastal mountain ranges. The eastern margin of Brazilian Highlands, known as the Great Escarpment, slopes abruptly toward the sea. A wealth of data indicates that Brazil was once joined to Africa. The lowlands of Brazil are composed mostly of undisturbed sedimentary rocks of alluvial origin. The coastal plain is narrow and discontinuous. This arrangement of landforms has acted as a deterrent to interior settlement. more |
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