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Looking at this aerial photo fully illustrates the idea of Ubin being our last wild frontier. It remains largely vegetated but interrupted with gaping pools of water that are the evidence of previous quarrying activities on the island. Granite hills on the island have all been carved into the lakes which we see today.
Lu, Wong and Chou writes in the Geology section of "Singapore's Biophysical Environment" that the granite of Pulau Ubin is part of the Bukit Timah Granite produced in early-middle Triassic age during the mountain building stage of the Malay Peninsula.
"The Bukit Timah granite refers to a wide range of acid rocks including the assimilation of basic rocks within the batholith. Granite is the main rock, light grey in colour and of medium grain size (3-5mm). The main minerals are quartz (30%), feldspar (60-65%) and ferromagesium minerals. Hybridization occurs at its western margin and the granite gives way to granodiorite.
The Pulau Ubin Granite has some differences from the Bukit Timah Granite. It is richer in minerals, e.g. green hornblende and brown biotite occuring in clusters. Inclusions occur commonly on Pulau Ubin and Changi, representing mainly the bodies of basic rock and these can vary from 1 cm to tens of metres."
This granite is also one of 3 major groups of rocks that were of economic importance to Singapore in the past. A series of granite quarries were located along the western flank of Bukit Timah and on Pulau Ubin. In 1970, there were 25 granite quarries employing about 1,200 workers in Singapore. The first quarry on Pulau Ubin opened in the early 19th century and the last quarry closed in 1999.