These are usually attributed to large scale sea level rises as the icy conditions of the Last Glacial Maximum (21,000 to 15,000 years ago) eased and sea levels rose.

I suspect that's broadly true, but they may also included memories of submarine landslide induced tsunamis, many of which occurred over the last 25,000 years along the Southern Queensland and Northern NSW coasts.

These tsunamis came about because of land collapses along the steeply sloping continental shelf.

These collapses sent great blocks of rock and sediment plunging down the steeply sloping shelf out to sea over distances up too 100km and depths of 3,000m. You can imagine the effects on sea levels.

While spectacular, these changes were only a small part of the challenges faced by Australia's Aboriginal peoples.

In my last column, I discussed what the Aboriginal occupation of New England might have looked like perhaps 40,000 years ago.

The Aborigines had arrived on the ancient continent called Sahul at a time when the climate was colder but damper.

From perhaps 25,000 years ago, the environment deteriorated significantly.

Globally, the ice spread. As it did, the climate became colder and drier, deserts spread and trees retreated. This climatic regime peaked during the Last Glacial Maximum 21,000 to 15,000 years ago.

Sahul became very dry, both intensely hot and intensely cold. Sea levels fell by 60 plus metres to perhaps 130 metres below current levels. Sea temperatures fell to 2-4 degrees C below those of today.

The effects across New England were dramatic. In the west, there were cold arid conditions. The deserts expanded eastwards. Stream flow was reduced. Trees and animals retreated. In the east, the falling sea levels revealed a rugged, inhospitable shore. While the coastal areas remained relatively well watered, food resources would have been reduced.

On the New England Tablelands, average temperatures fell by perhaps 8 degrees C. The Tablelands marked the start of a region of cold steppe and scattered sub-alpine woodland sweeping down through the southern Snowy Mountains into Tasmania, making it an inhospitable region for human habitation.

Faced with these changing conditions, the Aborigines would have been forced to retreat to refuge areas where food was still available. Some groups would have perished.

Better conditions lay ahead, but challenges had to be surmounted first.