As the Last Glacial Maximum (LGM) gripped the continent 21,000 years ago, the Aboriginal population was forced to adjust.
On the north coast, the fall in sea levels destroyed the environment that had formed along the previous coastline. Today, we are used to thinking of the north coast as a rich area in Aboriginal terms with its mix of sea, estuary, river and land resources. That may well not have been the case then.
The coastal shelf is often narrow and declines quite sharply. The falling sea levels destroyed the previous coastal environment and may have created a rugged coast line with increasingly cold waters, narrower rivers and smaller estuaries, a far less attractive environment than would exist later.
Inland, the Tablelands became sub-alpine, the arid zone widened, the inland lakes dried up, while the now smaller inland rivers wended their way across sandy plains. Faced by cold, very windy and dry conditions, the Aborigines probably retreated to refuge areas offering relatively better conditions.
The LGM began to ease around 15,000 years ago. Around this time, the North American ice sheets melted. Around 12,000 years ago, the Antarctic ice sheets began to shrink. The Holocene with its higher rainfall and warmer temperatures had begun.
The seas rose, reaching present levels around 6000 years ago. The first effect of rising sea levels was to again destroy the immediate coastal environment. It took time for the spreading rivers to begin to create the rich estuarine environment we know today.
Archaeological dates begin to reappear: around 9000 years in the Macleay Valley, 6500 years at Seelands in the Clarence, 5500 years at Graman on the Western Slopes. The oldest tablelands date we have definitely associated with human settlement is around 4300 years ago at Bendemeer. The Aboriginal society that the Europeans would find was forming.
Based on the date patterns as well as linguistic linkages, it appears that the tablelands were resettled from the coast. Two streams were involved.
The first group came from the south through the falls country from the new populations, the Dainggatti speakers, in the Macleay Valley. From there, they spread north.
As they spread, they coincided with settlers from the northern rivers and especially the Clarence/Nymboida river system, the Gumbaingirr speakers, who had followed the rivers upstream and effectively occupied significant parts of the Tablelands. Further north, there was Bandjalung expansion, but this appears to have been less pronounced.
The latter parts of the migration coincided with Gamilaraay expansion, creating an effective southern and western barrier. The end result was the very particular pattern of language distribution we see today, an elongated north-south pattern squeezed between east and west.
Jim Belshaw’s email is email@example.com. He blogs at newenglandaustralia.blogspot.com.au (New England life) and newenglandhistory.blogspot.com.au (New England history).