Friday, July 10, 2015

Bukit Gombak - The oldest region of Singapore Island.

There has been a lot of new developments around the old Hillview area these few years past. There's the upcoming Hillview MRT Station, the new HillV2 mall and of course more condominiums. Apart from the old primary school building, now reincarnated as the United Medicare Nursing Home, nothing structural was left of our old Princess Elizabeth Estate. The land where it once sat on is now flattened and levelled and presumably waiting for new developments.

But did you know that our old estate sat on land that is the oldest piece of rock found in Singapore geologically? Surprised? It sat on what is called the Gombak Norite which is 500 million years old.

If you look up Google Earth and see the continental shelf of South East Asia, you can see a flat area out at sea running from China near Hainan Island going down south along the Vietnam coast, across to Borneo and then south to Java and then following the coast up along Sumatra toward Myanmar.

Eons ago, it was believed that this entire region (excluding the Philippines, Suluwesi and the islands west) was all above sea level and the region was called in geology/geography as Sundaland.

Over the ages, tectonic and other geological forces created the mountains and countries and the melting ice age water made the sea level rise within Sundaland.

Five hundred million years ago, in the area which was to become Singapore Island, a small bulge known as the Gombak Norite arose.
(Norite is a type of rock like granite and is also found at Ponggol end and on Pulau Ubin.)

Another 250 million years would pass again before geological forces pushed up what is now known as the Bukit Timah Granite. Together these 2 rock formations would form the backbone of what would become Singapore Island.

Surrounding this central core, alluvial soil accumulated over the millennia and eventually shaped the island. Alluvial soil meant it was deposited by rivers and it is believed by geologists that the rivers that created the land was what is now the Straits of Malacca and the Singapore Straits before the sea level rose as a result of the melting ice. Interesting theory.

Princess Elizabeth Estate was built directly over this dome of norite rock and many ex-residents will remember the block of flats that they used to live in was built mostly with little foundation as it sat on the bedrock itself.

Photo of the old SIT Princess Elizabeth Estate with Bukit Gombak at its rear.

Addendum: August 2015.

I found this Youtube presentation which is an excellent explanation of the Sundaland flooding.
This was extracted from the blog "Atlantis in Java Sea" by Dhani Irwanto.

1 comment: