Cocos Island - Geology and Landscape

Geology and Landscape

Cocos Island is an oceanic island of both volcanic and tectonic origin. It is the only emergent island of the Cocos Plate, one of the minor tectonic plates. An Argon–Potassium radiometric determination established the age of the oldest rocks between 1.91 and 2.44 million years (Late Pliocene) and is composed primarily of basalt, which is formed by cooling lava. The landscape is mountainous and irregular and the summit is Cerro Iglesias at 575.5 m. In spite of its mountainous character, there are flatter areas between 200–260 m in elevation in the central part of the island, which are said to be a transitional stage of the geomorphological cycle of V-shaped valleys. With four bays, three of them in the north side (Wafer, Chatham and Weston), Cocos Island has a number of short rivers and streams that drain the abundant rainfall into them. The largest rivers are the Genio and the Pittier, which drain their water into Wafer Bay. The mountainous landscape and the tropical climate combine to create over 200 waterfalls throughout the island. The island's soils are classified as entisols which are highly acidic and could be easily eroded by the Island's high rainfall on the steep slopes, were it not for the dense forest coverage.