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The Australian Inland Sea

March 4, 2009

Detail of the map from A Friend of Australia, showing the "Supposed Sea". From the State Library of New South Wales.

Detail of the map from A Friend of Australia, showing the "Supposed Sea". From the State Library of New South Wales.

“In the case of penetrating the interior of Terra Australis, whether by a great river, or a strait leading to an inland sea, a superior country, and perhaps a different people, might be found

A Voyage to Terra Australis, Matthew Flinders

Inland Australia is defined by its lack of water. For lack of it, a continent roughly the size of the continental United States has one-fourteenth as many people—and it’s not as if all of the US is a paradise for human beings either. Before it was discovered the entire continent was a clearing house for cartographers’ fancies, but as Abel Tasman and James Cook and finally Matthew Flinders boiled down Terra Australis into merely Australia, the conjectures grew smaller too. The last big one to go down was the Australian Inland Sea.

Now of course, for Europeans, the continent started out as a prison. One of the attractions of Australia as a destination for convicts was there was no need for walls. With the ocean on one side and the Blue Mountains on the other, there was simply no place else to go. That was the theory, anyway, but in the early 1790s convicts started deserting.

Author David Levell has recently documented how the convicts came to believe a distorted version of the educated belief that Australia might be well-watered inland, and how that eventually fed back into the theories of the colony’s upper class decades later. Among the Irish convicts in particular the rumour began to spread that China was less than two hundred miles walk to the north. And so they started walking. In a matter of a few months a significant fraction of all of the transportee Irish in Australia were dead or missing.

Despite the losses, their idea spread and became something generally believed by all prisoners. With limited geographical education, they thought it would be possible to escape to the places they had heard were near Australia, such as Timor and New Guinea—not understanding that “near” is a relative term. Eventually they came to consider the Blue Mountains to the west as the boundary between New South Wales and another white colony somewhere in the interior. In a way reminiscent of American natives concocting tales of El Dorado and Cibola simply to get unwelcome Europeans to move on, Aborigines are known to have agreed with this last idea, spicing it up with the detail that the colony was on the shores of a large lake.

At the other end of Australia’s social scale those Aboriginal tales were mixed with a peculiarity of Australian geography to promote further belief in an inland sea. Between the first convicts deserting and later official expeditions, Flinders’ voyages had proven there was no large strait connecting the interior of Australia to the oceans. But there was another possibility: as explorers penetrated the mountains to the west of the colony, they found four large rivers (the Namoi, the Murray, the Murrumbidgee, and the Lachlan) which all flowed west or northwest toward the interior. As it happens they all eventually curve to the southwest, uniting in the Murray-Darling river system and emptying out into the Indian Ocean on Australia’s south shore. Before that was known, though, it was at least plausible that they emptied into a great lake in the interior, an antipodean Caspian Sea of sorts.

To settle the question several explorers made treks into the interior; two are worth mentioning. John Oxley went first, in 1817, and his discoveries were suggestive of something in the interior. His expedition explored the upper Lachlan River and discovered that as one went down it the land became marshy. He considered it impassable, and all the water seemed telling, but in reality it was just the Great Cumbung Swamp; on the far side the land returns to river, not a lake.

Charles Sturt was next in line, ten years later. He established that the sea, if any, must be further to the north, as he was able to travel the entire length of the Murrumbidgee to where it met the Murray, then down the remainder of the Murray to Lake Alexandrina (named for the then ten-year old princess who was to become Queen Victoria) and the river’s mouth. Edward Eyre would soon demonstrate that the largest body of water in the whole area was nothing more than the intermittent lake that would be named for him.

The strangest claims for the interior were made in the wake of Oxley’s first explorations, but before Sturt’s showed how the Murray dominated the southeast of the continent. In 1827, armchair explorer Thomas Maslen published the 428-page A Friend of Australia, “illustrated with a map of Australia and five plates”. The map is included at the top of this article, but an animated version, designed to highlight Maslen’s watery conjectures, can be found on the website of the State Library of New South Wales. Anticipating what Sturt would find out about the Murray, he believed that the more northerly rivers were the key to Australia’s inland waters. In his opinion, the various tributaries of the Darling River (as well as the Darling itself) would flow northwest into what he labelled the “Supposed Sea”. From there the waters would continue across the rest of Australia to King Sound in the far northwest, presumably ending in the mouth of the already-discovered Fitzroy River. The Fitzroy is, in fact, the longest river on that coast, but it’s about 1000 kilometers too short to fill the bill.

Eventually, the notion of a large inland sea was definitively killed by the expeditions of the ill-fated Burke and Wills and John McDouall Stuart. In the end, if you want an Australian Sea you can have one only if you’re a dinosaur or possess a time machine. 120 million years ago, as continental drift separated Australia from Antarctica, the east-central portion of Australia was lowered by as much as 350 meters. The ocean flooded the lowered land, forming the icy epeiric Eromanga Sea. The intrusion lasted for about twenty million years, and left its marks. That part of the world is famous for its opalized fossils of marine creatures and, more importantly for modern Australians, the basin filled with sediment over time. That sediment allowed the formation of the enormous Great Artesian Basin, which roughly corresponds to the sea which was once there, and on which 180,000 people rely for their water.

5 Comments leave one →
  1. Tim Brennan permalink
    April 15, 2010 2:18 AM

    Paul I am interested in your opinion on your conclusion that there is “no inland sea” – when today there is such a a vast body of water in the far west and lake Eyre that on face value would appear to be an inland sea. Cheers Tim

  2. Joshua_Australian permalink
    December 24, 2011 8:50 AM

    Create an inland sea that floods the interior of Australia.

    Use the inland sea as a safety valve capturing and releasing water depending on world climate conditions.


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