Amazon biome Amazonas, Brazil contains campinarana, dense rainforest and contact between campinarana and rainforest. The vegetation formations include terra firme forests and igapós. Submontane forests climb the first steps of the Guiana Plateau to about , followed by montane forests. Lichens and bromeliads are found up to . There is also alpine tundra in the tabular plateaus. The Amazon basin contains several large areas of moist forest, collectively called the Amazon rainforest. These are the Caquetá, Japurá-Solimões-Negro, Juruá-Purus, Madeira-Tapajós, Napo, Purus-Madeira, Solimões-Japurá, Southwest Amazon, Tapajós-Xingu, Tocantins-Pindara, Uatuma-Trombetas, Ucayali and Xingu-Tocantins-Araguaia moist forests. Each has distinctive vegetation. In the broad definition favored by
Amazon rainforest south as 45°. Climate fluctuations during the last 34 million years have allowed savanna regions to expand into the tropics. During the Oligocene, for example, the rainforest spanned a relatively narrow band. It expanded again during the Middle Miocene, then retracted to a mostly inland formation at the last glacial maximum. However, the rainforest still managed to thrive during these glacial periods, allowing for the survival and evolution of a broad diversity of species. During the mid-Eocene, it is believed that the drainage basin of the Amazon was split along the middle of the continent by the Purus Arch. Water