- Indonesia appeared from under the Southeast Asian seas as the result of the Indian and Australian plates colliding and slipping under the Sunda Plate, sometime in the early Cenozoic era around 63 million years ago.
Plate tectonics of Indonesia
- This tectonic collision created Sunda volcanic Arc that has produced chains of islands of Sumatra, Java and the Lesser Sunda Islands.
- The active volcanic arc creating super volcano that today become Lake Toba in Sumatra.
Lake Toba, North Sumatra
- The massive eruption of Toba supervolcano that occurred some time between 69,000 and 77,000 years ago instigated the Toba catastrophe theory, a global volcanic winter that caused a bottleneck (sharp reduction in the size of a population) in human evolution.
- Other notable volcanoes in Sunda Arc are Mount Tambora and Krakatau.
- The Indonesian archipelago nearly has present form in the Pleistocene period.
- Sundaland was still linked with Asian mainland that enabled the migrations of some Asian animals and hominid species.
- New Guinea island and the shallow seas of Arafura is the northern part of Australia tectonic plate and once connected as Sahulland.
Sundaland and Sahulland
- During the end of the last ice age (around 20,000–10,000 years ago), earth experienced global climate change; a global warming with the rising of average temperature caused the melting of polar ice caps and contributed to the rising of sea surface.
- Sundaland was submerged under shallow sea, creating Malacca Strait, South China Sea, Karimata Strait and Java Sea.
- During that period, Malay peninsula, Sumatra, Java, Borneo and the islands around them were formed.
- On the east, New Guinea and Aru Islands were separated from the Australia mainland.
- The rise of sea surface created isolated areas that separated plants, animals and hominid species, causing further evolution and specification.