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Overview
| The
Birth of the Island
| Reefs
and Coastlines
Volcanoes
| Lakes
and Rivers | Climate
Sulawesi is one of the largest of the thirteen thousand islands or more that make up the archipelago of Indonesia. The island is located between 119 degrees east and 126 degree east longitude and between 7 degrees south and 5 degrees north latitude. Formally the island was known as the Celebes.
Sulawesi lies in the shallow seas on top of
the Sunda shelf, a submerged projection of the Asian continent, and is
grouped with the large islands of the archipelago, Sumatra, Java, Kalimantan
and Bali, which also lie on this shelf, in the Greater Sunda Island complex.
Until recently, it was widely believed that the Malay peninsula, Java, Borneo, and the western part of Sulawesi were part of Laurasia, while the eastern part of Sulawesi and the eastern islands of Indonesia were part of Gondwanaland.
However, scientists have recently concluded that Tibet, Burma, and the Malay peninsula were part of Gondwanaland, and that they broke away from the margin of the Australasian part of the continent around 200 million years later. Twenty million years later, it is theorised, Borneo broke away from Gondwanaland. Then, approximately 90 million years ago, eastern Sulawesi, Papua-New Guinea, and Australia broke away from the Antarctica, and began a leisurely journey north, travelling at approximately 10cm a year.
Then, fairly recently in geological terms, a mere three million years ago, western Sulawesi collided with what is now western Sulawesi, ramming it and causing the Southwest peninsula to rotate counter clockwise. The collision resulted in the Gulf of Bone between the South and Southeast peninsulas of Sulawesi.
The collision of continents that that resulted in Sulawesi has left the island with active fault lines, and the island is still moving and changing shape. It is possible that in the future, the island will fragment, and become an archipelago of small islands separated by narrow straits.
The island is surrounded by thousands of smaller islands, at least 110 of which have an area of 1.5 km or more.
There are also coral reefs in abundance. In the Spermonde archipelago alone, there are 16,000 sq. km, and there are also large areas of reef off Manado and Bunaken in the north. These sites are well-known among the international scuba diving set, and boast world class diving facilities. The coral reefs around the Togian islands are less well known, but are unique in Indonesia, containing all major types of reef environment: fringing, barrier, and atoll.
The volcanic debris of the extinct volcanoes
in the south have made it one of the most fertile areas of the island.
Sulawesi has eleven volcanoes that are listed as active, most of them in
the north, and many fumaroles and volcanic springs. The most active volcanoes
in recent years have been Soputan-Aeseput, Lokon-Empung, and Gunung Api
Siau. When Mount Awu exploded in 1966 on
Sangihe Island, more than seven thousand
people died. In 1983, a massive eruption tore apart the island of Una Una
in Tomini, sending ash fifteen kilometres into the sky, and spreading it
as far as south-east Kalimantan. In 1991, an explosion on Mount Lokon killed
a Swiss doctor who
wandered too close.
These volcanoes are the result of the collision of continental plates. The land under the sea north of Tolitoli and east of Minahasa is moving under enormous pressure. The heat generated is such that rocks melt, and on occasion, this molten rock finds its way through a weak point in the earth's surface, and a volcanic explosion results.
Unlike Borneo and Sumatra, there are no long rivers in Sulawesi. The longest is the Lariang, which flows into the Makassar strait, and is only 200 km long.
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