Reunion island, France

Gorges created from volcanic fractures, like the bed of the Bras de Caverne river, make access to the center of the island of Réunion difficult. Some sites were explored only recently, such as the “Trou de Fer,” a ravine of 820 feet (250 m) that was discovered in 1989. Because the island’s center was protected from human encroachment, its tropical forests, with giant heather, ferns, and lichens, have been preserved, whereas the forests at low altitude have been converted to agricultural or urban use and have disappeared. More than 30 species of animals and plants, of which about two-thirds were endemic, have become extinct on the island in the past 400 years. The destruction of the forest and the introduction of non-native species have a serious impact on these insular ecosystems, whose balance has been created without outside influences. On the island, the dodo became extinct shortly after the arrival of Western sailors, who brought cats, rats, and pigs with them.