Geologically, Singapore can be considered as an extension of the Malay Peninsular, and together with the surrounding region on the east, forms a stable crustal block, termed Sundaland. The oldest rocks in Singapore probably come from the Palaeozoic era, which ended about 225 million years ago.
Granite occurs in two separate masses.
The larger one is found in the central and northern areas, the smaller one in parts of northeastern Singapore. Granite or igneous rocks underlie the Bukit Timah Nature Reserve and the Central Catchment Area in the centre of the island. The granite in Singapore, according to radioactive age determination, is more than 200 million years old. The sedimentary rocks of the Jurong Formation skirt the central granite and form extensive areas in southern, southwestern and western Singapore. These variations of conglomerate, sandstone and shale are also found on the islands to the south and west.