Visit Rio!: Nature

Ilha Grande, Angra dos Reis, RJ

Lagoa Rodrigo de Freitas, Rio, RJ

The landscape of the state of Rio de Janeiro is inscribed in the domain of the “Sea of hills”. Its ancient crystalline massif shields have been extremely eroded while exposed to weathering, which created a typical grouping of “half-orange” hills, all covered by the Atlantic Rainforest.

Its coastline is, thus, characterized by beaches interrupted by rock massifs, bays, rivers’ mouths and lagoons. And the city of Rio fits well in this description, with its main landmarks as Precambrian outcrops in direct contact with the ocean!

Precambrian corresponds to the first 4 billion years of planetary history.

The Precambrian crystalline rock massifs are called shields.

In the constitution of these shields, bundles of magmatic rocks can be distinguished, originated from cooling and crystallization of mantle material during the Archean.

Granite is the most common of these rocks and is present along with the Gneisses in the basement of the continents.

Tree-ferns are testimonies of ancient times and are widely spread in the Tijuca Forest, the largest urban forest in the world.

Tree ferns have a lengthy fossil record stretching back to the Triassic Period (251 to 199.6 million years ago). Members of both Cyatheaceae and Dicksoniaceae appear to have been diverse and relatively common during the succeeding Jurassic Period (199.6 to 145.5 million years ago) and Cretaceous Period (145.5 to 65.5 million years ago). However, the modern genera only become evident during the early Cenozoic (65.5 to 2.6 million years ago).

The Mata Atlântica itself was formed by Paleoclimatic humid and dry cycles in the Quaternary Period (the last 2,5 million years), which created a wide variety of environments, contributing for the large biological diversity and ecosystems within tropical forests, with a high degree of endemic species.

Endangered species,