Climatological changes during the Late Pleistocene and beginnings of the Holocene that affected Papua New Guinea

During the last million years the Pacific Ocean has suffered great climatological changes as a direct result of the glacial periods. During the glaciations the average temperature of the sea decreased between 6 and 10 degrees Celsius and a big part of the surface of the ocean frosted, shaping enormous ice coats surrounding the poles and vast glaciers in Europe and North America. The great amount of frozen water caused a decrease in the level of the sea close to 115 meters under the actual level. For this reason, most of the platform that surrounds the Australian continent, a surface near to 2,5 millions of Km2, remained over the sea level, which turned out in being almost joined with the southern Asia.

62,000 years ago the sea level reached a height of about eighty five meters under the current level; the Australian continent extended itself then from Ecuador till the latitude 43º south, reaching an extension of 10 million squared kilometers and joining all the neighboring islands, like New Guinea, New Ireland and the Bismark archipelago and Tasmania among others. At that time the current Indonesia was only an extension of the Asian continent and it was possible to walk from Myanmar to Bali; while Australia and New Guinea were joined forming a unique great mass of earth known as “The Great Australia”.

Figure 1: Sea level evolution during Pleistocene and Holocene. (Chapell, 1976.)

In between both lands a region is defined which includes thousands of small islands and rocky isle denominated Wallacea, after the geographer Alfred Russel Wallace who during the XIX century defined the area that separates both fauna. Sahul and Sunda were separated by the strait of Sunda that segregated the Timur island of the “Great Australia”. This strait measured between 90 and 100 kilometers wide, enough so that each territory was not visible from the opposite shore and which made it impossible for terrestrial animals to cross. Nonetheless, there exists currently, just as in the past, numerous migratory birds that every year make the trip between the two lands.

Figure 2: Bio-geographic divisions of Indo-Malaya, with the location of the chosen archeologic places, dating 30.000 B.C.