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Mammal dispersion as an indicator of Sea Levels


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 rise.


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 years ago.


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 vegetation.


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.


Hydro-thermal expansion?


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.




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Page 5
The above image shows how the
Indonesian archipelago would have looked
120,000 years ago, with land-bridges
connecting most areas.
Graph of Orbital Periods
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Click to enlarge
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