These
igneous
intrusive
rocks (also called plutons) cooled and crystallized deep below the Earth's surface (10 - 20 km).
Erosion and tectonics, during the last 500 million years, brought them up to the Earth's surface and made them visible to us.
They are nowadays covered by dense
submontane and
montane
tropical rainforest.
Some ruins, partly covered by the lush vegetation of the Atlantic rainforest, remember
Ilha Grande's dark
history
as a shelter for pirates, a center for contraband slave trade, a quarantine hospital
and a high securitiy penitentiary.
During the last years, Ilha Grande with its 106 beaches, 14 bays, 4 lakes, 10 rivers and 3 grottos,
has become one of the most visited
ecotourism locations
in the state of Rio de Janeiro. Several rainforest
trails
take the hiker to the most isolated places of the island.
See also:
guided tours