Introduction to
The Land Bridge
We tend to think of Australia, as it is currently called, as having been moulded forever in the familiar island shape we have known since we were children.
And yet, in very recent times (in geological terms), the coast extended further than it does today. Between about 70,000 and about 15,000 years ago, towards the end of the geological epoch called the Pleistocene, Australia was larger than it is now. Sea levels were lower. At the most expansive point, there was about 30% more exposed dry land than there is today.
This created connections between places we now think of as separate.
In the north, the islands of southeast Asia weren’t so much islands as fingers of land reaching towards the Top End of Australia, with only the barest barrier of sea between. New Guinea and the Torres Strait Islands were linked to mainland Queensland by a stretch of land now submerged under the Torres Strait.
In the south, Lutruwita/Tasmania and Victoria, as they are currently known, were joined by land which now lies 60 metres under the cold, treacherous seawater of the Bass Strait.
Ancestry of First Nations Peoples still reflects these past connections.
Coastlines expanded across the continent because the Earth was experiencing an ice age. It got so cold that when water evaporated from the world’s rivers and oceans, it returned to earth not as rain but as snow. The world’s water was frozen, and it built up into massive polar ice sheets and glaciers. Scientists estimate that the ice started building about 115,000 years ago. As the ice expanded, sea levels gradually shrank.
(This was a global cooling climate event, the opposite of what we are experiencing today with human-induced climate change and associated warming, polar ice melting and sea level rises.)
Sea levels fluctuated up and down, but the general trajectory was for sea levels to fall. As sea levels dropped, parts of the relatively shallow Bass Strait seafloor became exposed as land. Starting from about 65,000 years ago, but most consistently from about 43,000 years ago, the sea fell enough that a continuous land connection existed between Victoria and Lutruwita/Tasmania.
This land is called a land bridge, as it enabled people and wildlife to cross from one side to the other. But the land was more than just a bridge. Scientists like to call it the ‘Bassian Plain’ because the exposed lowlands were vast. At its most expansive, the land bridge was about as big as Lutruwita/Tasmania is today, a broad landscape large enough to be a small European country. It existed in this form for many thousands of years.
The sea continued to fall, and the exposed plain to expand, until between about 29,000 to about 18,000 years ago, when the climate reached its coldest point. From then on, global temperatures warmed, the glaciers melted, and water was released back into the oceans. After around 15,000 years ago, sea levels began to rise quite rapidly, reflooding the low-lying coastal areas of the Bassian Plain. It took about a thousand or more years for Lutruwita/Tasmania to be separated from mainland Victoria, and another few thousand years for the main islands of the Bass Strait to emerge.
Animated 3D flyover of the contours of the Bass Strait showing the former eastern edge of the land bridge, flying over the high points of modern-day islands of Tayaritja/the Furneaux Group of Islands, the Kent Island Group, the Hogan Island Group, and Yiruk/Wamoon/Wilsons Promontory. Created by Geoscience Australia.
Map of the ancient extended continent joining Australia to New Guinea and Lutruwita/Tasmania, which scientists have named ‘Sahul’, dating to about 65,000 to about 15,000 years ago. This map compares the locations of Australia’s modern capital cities, the oldest known archaeological sites in Australia, and computer-modelled likely migration routes of First Peoples across the continent. Map by Megan Hotchkiss Davidson, Sandia National Laboratories, drawing on data developed by the Australian Research Council Centre of Excellence in Australian Biodiversity and Heritage (CABAH).
Ancestors of First Nations Peoples witnessed these events.
How long have People lived on land bridge Country? Western scientific and First Nations perspectives diverge on this question, although both agree that People have lived here for a very long time, amounting to thousands of generations.
First Nations knowledge states the Old People lived on Country since People began.
Western based scientists, drawing on current archaeological and genetic evidence, estimate that First Peoples arrived in Australia around 65,000 years ago. They speculate these Peoples likely had to travel over the sea from southeast Asia before landing in northern Australia. They then moved south and west across the continent. By around 40,000 years ago, People had reached the southernmost parts of Australia, including Victoria, the Bassian Plain, and Lutruwita/Tasmania.
When the Bassian Plain reflooded and the land bridge was broken, Peoples were separated from each other and their former Land Country by the rising sea. Because the Bass Strait seafloor is reasonably flat, the final flooding of the strait may have happened quite quickly. Scientists estimate the land could have been swamped by over 20 metres of seawater per year.
It is plausible to imagine someone who crossed over the bridge on a four- or five-year overland journey finding themselves permanently cut off when they tried to return.
The last connecting point of the land bridge, not far from modern day Yiruk/Wamoon/Wilsons Promontory, may have first turned into a difficult to traverse tidal marshland before becoming open sea.
Eventually, what had once been a broad plain became an impassable strait of water.
The final land bridge connection was broken by the sea at a point southeast of Yiruk/Wamoon/Wilsons Promontory between about 14,000 and about 12,000 years ago. Pictured is Shellback Island in the Bass Strait just off the coast of Yiruk/Wamoon/Wilsons Promontory. Photograph by Mark Antos. ©Mark Antos. Courtesy of Parks Victoria. CC BY-ND 4.0.
An animated reconstruction of the changing landscape of the Bass Strait from 100,000 years ago to the present day. Created by the Deakin University Marine Mapping Group drawing on Geosciences Australia bathymetry data. With thanks to Daniel Ierodiaconou.
First Nations communities of land bridge Country have oral traditions, stories and songlines connected to the times of the land bridge which have been kept for thousands of years over generations. The songline of the whale is kept within many coastal communities and connects to stories of ancient sea level change. Picture: Envato Elements.
The former inhabitants of the land bridge had to adapt to their new environment or leave in order to survive. This rocky outcrop on a small island in Tayaritja/the Furneaux Group was once a hilly ridge overlooking the Bassian Plain. Photograph by Simon Haberle. CC BY-NC-ND 4.0.
After the waters rose seabirds used the islands of the Bass Strait for breeding. The shy albatross, pictured here, is an endangered species which breeds only off the coast of Lutruwita/Tasmania, including on Albatross Island in the western Bass Strait. Photograph by Ed Dunens. CC BY 2.0.
The Bass Strait is a narrow, shallow seaway off the southeastern coast of Australia. It connects the Southern/Indian Ocean and Tasman Sea and separates mainland Australia from the island of Lutruwita/Tasmania. It is 500 kilometres long and 350 kilometres wide, with an average depth of 60 metres. Between about 65,000 years ago and about 15,000 years ago when sea levels were lower, parts of the Bass Strait were exposed as land and a land bridge existed between mainland Australia and Lutruwita/Tasmania.
Today, Bass Strait is an at times unpredictable and volatile stretch of sea populated by diverse marine life.
Between Yiruk/Wamoon/Wilsons Promontory in southeastern Victoria and the land of northeast Lutruwita/Tasmania lies an archipelago of over a hundred islands. These islands were once hills and high country of the northern and eastern Bassian Plain. On the other side of the strait, King Island marks what was once a high ridge on the western edge of the Bassian Plain.
The rising seas brought significant change. New wildlife such as whales, seals, corals, seagrass, fish, and seabirds came to the waters and islands. The former land-dwelling inhabitants of the bridge – the mammals, birds, reptiles, plants, and people – had to adapt or leave in order to survive.
While there is much we don’t know, researchers have found and continue to find different types of evidence revealing what the land bridge was once like and about what lived upon it. For instance, pollen counts extracted from island lagoons tell us the type of plants which commonly grew in different areas.
We know there were rolling sand dunes on parts of the Bassian Plain because they remain etched on the seabed. Hi-tech underwater marine mapping of the Bass Strait clearly shows them: the outline of former sand dunes now calcified into coral encrusted rocks.
Fossil records, gene patterns and the geographic distribution of animals on the mainland and the islands reveals the presence of wildlife populations which once were linked by the land bridge, and which became isolated by rising seas.
And there is archaeological evidence of human occupation of the land bridge during the ice age, excavated from caves and other former shelters on what were once high points in the Bassian Plain.
Tayaritja/the Furneaux Group of Islands in the eastern Bass Strait appears to have had a community of people living on it after the plain flooded and separated them from both sides of mainland Victoria and Lutruwita/Tasmania. People lived there and managed the island’s resources for at least 5,000 years after the sea levels rose, before seemingly disappearing from the archaeological record around 4,000 years ago.
Today, First Nations communities that neighbour the coast and live on the islands of the Bass Strait hold unique insights into the Sea Country which was once land. Their knowledge, though fragmented by the violence of European invasion, has been assembled over many generations. This knowledge extends back to the times of the Old People of the land bridge era through songlines and dreaming stories which hold tantalising references to sea level change.
First Nations scientists and communities in Victoria and Lutruwita/Tasmania today are working with other scientists to try to understand this deep past. Together, they are exploring how the findings of Western science can combine with Traditional Knowledge to paint a picture of the agency, environment and lifestyle of the Old People prior to colonisation, reaching back to the land bridge era.
Knowledge of First Nations management practices informs all of us how to better care for Sea and Coastal Country, giving valuable clues on how to adapt to climate change and other challenges of the present.
A view from a small island in Tayaritja/ the Furneaux Group of Islands. Photograph by Simon Haberle. CC BY-NC-ND 4.0.
Today, scientists and First Nations communities work together to piece together the stories of the deep past. Here, researchers at the Australian National University and members of the Palawa community undertake coring samples of a lake on Truwana/Cape Barren Island to research how fire was used by Old People to manage the landscape. Photograph by Jillian Mundy. ©Jillian Mundy. All rights reserved.
Core sample taken from a lake on Truwana/Cape Barren Island in Tayaritja/the Furneaux Group of Islands. Photograph by Jillian Mundy. ©Jillian Mundy. All rights reserved.

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