Quarries Since the British founding of Singapore, the island has been known for its granite. The numerous granite quarries on the island supply the local construction industry. The granite outcrops are particularly spectacular from the sea because their grooves and fluted sides create furrows and ridges on each granite rock slab. These features are captured in John Turnbull Thomson’s 1850 painting — Grooved stones on Pulo Ubin near Singapore. The granite from Pulau Ubin was used in the construction of Horsburgh Lighthouse. Tongkangs ferried the huge rock blocks (30 by 20 feet) from the island to Pedra Branca, the site of the lighthouse, in 1850 and 1851. Later, the granite was also used to build the Singapore-Johor Causeway. Most of the quarries are not in operation today and are being slowly recolonised by vegetation or filled with water. Apart from quarrying, farming and fishing were the principal occupations of the inhabitants of the island in the past. It is also called Selat Tebrau (tebrau is a kind of large fish). In the 1970s as the granite quarries closed down and jobs dwindled, residents began leaving.