Brazil of shields, Brazil of basins
Brazil is made up of two types of geological structures: shields and sedimentary basins.
Shields. There are three main shield regions: the Guiana Shield in the north of the country, the Central Brazilian Shield in the central-northern and southern regions, and the Atlantic Shield in the central-eastern region. They make up 36% of the Brazilian territory. From a geological point of view, they are made up of crystalline metamorphic or magmatic rocks, characterized by their resistance to erosion. They represent a type of geological formation generally found in low-lying areas. It is from these shields that the sugar loaves and other "chapadas" emblematic of the Brazilian landscape were carved. Unlike the surrounding countries, which are affected by the movements of the Andean fault, the presence of cratons over a large part of the Brazilian territory is the reason for the country's great geological stability.
The shields are of major economic interest to Brazil, whose economy is partly based on the mining sector. It is in the shields that the main metallic deposits of iron, manganese, copper, bauxite and cassiterite are found; such as those of the Iron Quadrilateral in Minas Gerais or the Serra de Carajas, which contains 18 and a half billion tonnes, the world's largest reserves of ferrous ore.
Sedimentary basins. The remaining 64% of Brazilian territory is made up of sedimentary basins. These are depressions filled with sediment and rock, transported during the erosion process and accumulated during the sedimentation phase.
These basins differ in size and age. They may be large (the Amazonian basins of the São Francisco River and the Pantanal) or smaller (the Bahian Recôncavo, São Paulo and Curitiba). Some are ancient, having formed during the Paleozoic (São Francisco, Paraná and Recôncavo). Others are more recent, formed in the Tertiary (Central and Coastal Basins) and Quaternary (Amazon Basin and Pantanal). In addition to their value in terms of biodiversity and landscape, these basins supply a large proportion of the country's fossil fuels (coal and oil).
Regions with marked geological specificities
The Amazon, a vast plain. The Amazon occupies a large part of northern Brazil. It consists mainly of a vast plain 3,500 kilometers long and between 600 and 1,200 kilometers wide. Paradoxically, it is in this region of plains and sedimentary basins that we find Brazil's highest peak, Pico da Neblina, which rises to an altitude of almost 3,000 metres in the Guiana massif. The Amazon and its tributaries are born in these areas below 200 metres. The lowest areas bordering the world's most powerful river will flood during the rainy season. The higher terraces are vast unsinkable zones where you can venture out at any time. The river and its major tributaries will become major navigation routes that large boats can sail thousands of kilometers upstream. On its banks, the relief of the Amazon makes the rivers more impetuous and marked by numerous waterfalls.
Nordeste, beach, cliffs and chapadas. The Nordeste region is prized by tourists for its natural beauty. In its western part, it offers the chapadas of Maranhão, Piauí and Ceará, with the Serra d'Ibiapaba and the Butte d'Araripe, plateaus with often modest relief and typical tabular shapes. They can rise to 1,600 or even 1,800 metres in the magnificent Chapada Diamantina (Bahia). The coastline is lined with dunes, offering spectacular scenery, as in Ceará, or with lagoons. Tertiary low plateaus, known as tabuleiros, line the coasts and form spectacular cliffs, postcards of the Nordeste, as at Canoa Quebrada or Pipa.
The Centroeste, the Brazilian plateau. The Brazilian plateau is the country's second most important structural unit. It is an immense area of flattened land that has been raised and tilted to the west, south and north. Its location makes it a veritable water tower for Brazil, the birthplace of many powerful rivers and their tributaries. Appearing as a watershed, the rivers that form in its northern part join the Amazon and its tributaries, while in its southern part, they join the Paraná basin. This plateau with its often flat horizons is bordered by chapadas, offering a variety of landscapes to these cerrados lands. The alluvial plain of Paraguay, to the south, is a vast depression now much sought-after by ecotourism enthusiasts: this is the Pantanal, fed by the waters of the Serras and Chapadas and transformed into swamps during the rainy season. Today, the uncontrolled exploitation of the cerrados by Brazil's production-oriented agriculture, particularly soya, is threatening the region through the pollution it generates.
Sudeste: land of highlands. The Southeast or Sudeste has been shaped by powerful uplifts of the basement. The rugged crystalline massifs offer travelers a mountainous landscape, a sensation heightened by winter temperatures that can sometimes be negative, and where villages take on an Alpine air with their Bavarian-roofed houses. These highlands are bordered by often narrow coastal areas. These coastal areas can resemble low plateaus, hills or coastal plains. These areas have played a major role in the history of Brazilian settlement. In terms of ecotourism and sports holidays, the traveller will find many choice destinations: the Serra d'Espinhaço culminates at 1,800 metres. The Serra do Mar and Serra da Mantiqueira, which rise to 2,890 meters, also offer superb landscapes, sometimes extended by coastal reliefs that flow spectacularly into the sea in the bays of Guanabara, Angra dos Reis, Santos or Paranaguá.
Southern Brazil, mountains and plains. Southern Brazil and the state of Rio Grande do Sul are known as gaucho country, like neighboring Argentina. The southern part of this state consists of a plain, formerly dedicated to livestock farming, as in Argentina. Buttes pierced by rivers and basalt escarpments make up the mountainous areas known as Serra Geral, dotted with canyons such as Itaimbezinho, a favorite with ecotourists.
The main mountain ranges of Brazil
Around ten Brazilian massifs have one or more peaks that exceed two thousand metres in altitude. What some might think of as cow mountains are in fact areas of immense tourist potential, and of every level of difficulty.
Serra do Imeri. With its Pico da Neblina, this is Brazil's highest peak at almost 3,000 metres. Difficult to access in the Amazon, it is a highly technical biodiversity spot. Climatic conditions are extremely changeable.
Serra do Caparaó. Peaking at 2,891 meters in the heart of the eponymous national park, this is the most sought-after massif for Brazilian mountaineers. Walks in the heart of the Atlantic forest offer the chance to observe a wealth of flora and fauna.
Serra da Mantiqueira. The Serra da Mantiqueira, which stretches across the states of Rio, São Paulo and Minas Gerais, has peaks rising to over 2,800 metres, in the Agulhas Negras massif national park. Abundant rainfall brought by the trade winds and a wide temperature range have also led to the development of exceptional flora and fauna.
Serra do Mar and Serra dos Orgãos. These two contiguous massifs, over 2,000 metres high and stretching from Rio to Rio Grande do Sul, are distinguished by the photogenic quality of their peaks: the sugar loaves of the Serra do Mar contrast with the sharp peaks of the Serra dos Orgãos.
Serra do Caraça and Serra do Espinhaço. These two contiguous massifs in Minas Gerais have left their mark on Brazilian history, as their mineral wealth in gold and diamonds was the driving force behind the development of colonial towns such as Ouro Preto and Tiradentes, with churches laden with the treasures of mineiro baroque, designed by the skillful hand of the Aleijadinho.
Chapada Diamantina: one of Brazil's ecotourism treasures. In the state of Bahia, these magnificent tabular reliefs approaching 2,000 metres in altitude surround numerous valleys, such as the Pati Valley, and small colonial towns like Lençois that recall the region's eponymous mining past. The Chapada Diamantina is like a water tower in the Sertão. History, geography and ecology form an indissociable whole here, which more and more nature lovers are visiting every year.
Waterways in Brazil
Brazil is inextricably linked with its rivers. The Amazon is the mother of all myths, while the Rio São Francisco is affectionately known as "Old Chico" or the river of national unity. Brazil accounts for 13% of the world's freshwater. The country faces numerous environmental and human problems. Dams, the destruction of riverside vegetation, water pollution, over-exploitation of aquatic resources and environmental destruction are just some of the challenges the country faces in maintaining its endangered water heritage. River ecotourism opportunities are developing in the Amazon and Pantanal. This is an extraordinary opportunity to meet local communities and the environment.
The Amazon Basin. This is the world's largest river basin. It is home to the Amazon, the planet's longest and most powerful river. Originally known as the Solimões, it was after its meeting with the Rio Negro at Manaus that it took on the name Amazon River. Other tributaries of the Amazon, such as the Purus, Madeira, Tapajós, Xingu, Juruá and Jari, are among the world's great rivers.
The Tocantins-Araguaia basin. This is the other major Amazonian basin, whose characteristics include containing two of the planet's largest river islands, the Bananal and Marajό islands.
The São Francisco basin. A "historic" 2,800-kilometer river, it is the only permanent river in this desert region of the Nordeste. A vital resource for the region, it is in great danger, as it is channeled and overexploited to irrigate the region's crops. The film Espelho d'agua shows the beauty of the landscape and the richness of the communities living along its banks.
The Paraná-Paraguay-Uruguay basin. Stretching over 2,400 navigable kilometers, the Paraná provides much of the region's energy. The Itaipu binacional hydroelectric dam has long been the world's largest. The Paraguay River crosses the Pantanal and is one of the country's major waterways.
