Pulau Langkawi
Langkawi, a cluster of 99 islands separated from mainland Malaysia by the Strait of Malacca, is a district of the state of Kedah in northern Malaysia and lies approximately 51 km west of Kedah. The total land mass of the islands is 47,848 hectares. The main island spans about 25 km from north to south and slightly more for east and west. The coastal areas consist of flat, alluvial plains punctuated with limestone ridges. Two-thirds of the island is dominated by forest-covered mountains, hills and natural vegetation.
The island's oldest geological formation, the Machinchang Formation, was the first part of Southeast Asia to rise from the seabed in the Cambrian more than half a billion years ago. The oldest part of the formation is observable at Teluk Datai to the north-west of the island, where the exposed outcrop consists of mainly sandstone ( quartzite ) in the upper parts and shale and mudstone in the lower parts of the sequence. [26] In fact, the best exposure of the Cambrian rocks (541 to 485 Ma ) in Malaysia is the Machinchang Formation – made up of quartzose clastic rock formations – in Langkawi; the other known correlative, the Jerai Formation, crops out near to the west coast of Kedah on the mainland (peninsula). [27] Geologically speaking, all these rocks are located within the Western Belt of peninsular Malaysia, which is thought to be part of the Shan–Thai Terrane.