The Land Bridge
Anyone who has ever sailed Bass Staright would be acutely aware of how the profundity of the Southern Ocean rises up almost vertically on either side of Bass Strait to create a shallow waterway of steep waves and vicious currents.
Well now there is a way to explore the strait from the comfort of your armchair… and it’s a fascinating journey.
A newly launched digital project: The Land Bridge Managed and designed by Wind and Sky Productions, is a fascinating free online community education resource, telling the story of the ice age land bridge which once connected Tasmania and Victoria across what is now Bass Strait.
Here’s a sample…
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.
You could spend a few hours exploring this site…
And it wouldn’t be wasted!
Or if you are the sort of person who prefers their inputs to be purely visual, spend 24 minutes watching this engrossing documentary.