The distribution of species of mammals which exist on islands now cut off from other
landmasses by shallow seas can also give us an indication of the rate of sea level
The Falkland Island Fox (Dusicyon australis) which was hunted to extinction in the
nineteenth century can only have got there by walking across from Argentina, a distance
of some 500 km, on the now submerged shelf. The waters on this shelf are up to 200
metres deep but this depth could have been reached in less than 120,000 years.
Sumatra and Borneo must have been linked by a continuous forest ecosystem for the
two almost identical species of Orang utan to exist. The waters of the Karimata Strait
between Sumatra and Borneo are about 40 metres deep and this means that speciation
into Pongo pigmeus (Borneo) and Pongo abelii (Sumatra) could have come about in the
last 22,000 years.
Macaques are monkeys found on most islands of the Sunda Archipelago including Sulawesi
and the Philippines where waters separating them are up to 2000 metres deep.
This suggests that macaques were distributed among these islands at least 1.1 million
The small buffalo (Bubalus) is also endemic to many of these islands and they must
have radiated out from Asia in the same way.
Fossils of the buffalo (Bubalus mindorensis) discovered in a karst cave in the Philippine
Island of Mindoro confirm that these animals were not introduced by man.
The depths of the straits and seas between the islands of the Indonesian Archipelago
and the estimated times for when there were land bridges - are as follows
Java Sea 40 m 22,000 years
Karimata Strait 40 m 22,000 years
Makassar Strait 2000 m 1.1 million years
Luzon Strait 2500 m 1.38 million years
Taiwan Strait 70 m 38,000 years
Mindoro Strait 400 m 222,000 years
Arafura Sea 80 m 44,000 years
Suggestions of animals ‘rafting’ between landmasses are a preposterous notion; only
insects and perhaps some rodents could disperse in this way - on or within floating
Other Previous Land Bridges
The Straits of Gibraltar are 900 metres deep. A land bridge between north Africa
and Europe will have existed around 500,000 years ago. Gorham’s Cave, on the south-eastern
side of Gibraltar, is now at sea level but will have been at least 45 metres above
it when it was inhabited by Neanderthals, 25,000 years ago. This suggests that there
may be more caves which are now submerged where Neanderthals or even earlier man
lived. The University of York, in fact, is currently researching the caves in a submerged
reef off Gibraltar.
The Bering Strait between Alaska and Asia is less than 50 metres deep and so a land
bridge will have existed less than 30,000 years ago.
An Indicator for Energy Reserves?
If indeed areas between the Indonesian Archipelagos supported a continuous dense
rainforest before their submergence, a great deal of fixed carbon should have accumulated
in the form of petroleum and gas reserves.
Some scientific opinion suggests that sea-level rise is caused by expansion of water
as temperatures rise (supposedly by global warming). Water, above 4 degrees C. has
a coefficient of expansion of 0.00021 per degrees C. rise.
My modelling suggests that mean temperatures (see graph on orbital periods) have
risen by 33 degrees C. during the last 330 million years and this equates to around
0.1 degree C. per million years. This would account for just 2.5 trillion extra
litres per year, compared to the extra 650 trillion litres of water I estimate as
currently being produced each year.
THE ACCUMULATION OF WATER
The above image shows how the Indonesian archipelago would have looked 120,000 years ago, with land-bridges connecting most areas.