Taking it to the edge: did you know? The inland sea - impetus for exploration

''What then can be the nature of that mysterious interior, bounded as it is by a table-land without river and lakes, without watercourses or drainage of any kind, for so vast a distance? Can it be that the whole is one immense interminable desert, or an alternation of deserts and shallow salt lakes like Lake Torrens?''

EJ Eyre Journals of expeditions of discovery into Central Australia…London: T. and W. Boone, 1845 volume 2 p. 128

Almost from the time of the earliest discoveries of Australia's coast there were hypotheses about the interior of the continent: it was divided into two or more large islands; there was a huge inland sea, such as the Mediterranean or Caspian; or there was a great river which would provide a route to the interior.

In his Introduction to A voyage to Terra Australis Matthew Flinders recounts some of these hypotheses. His instructions from the Admiralty clearly had a strait connecting the north and south coasts in mind: '…in case you should discover any creek or opening likely to lead to an inland sea or strait, you are at liberty either to examine it…' volume 1, (page 8). The apparent lack of major rivers reaching the ocean was also considered to result from Australia being 'composed of two or more islands, as had formerly been suspected by the Dutch, and by Dampier: whilst others, believing in the continuity of the shores, thought this want might arise from the interior being principally occupied by a mediterranean sea; but it was generally agreed, that one end of the separating channels, or otherwise the entrance, if such existed, into the supposed sea, would most likely be found in this unexplored part of the South Coast' (Introduction pages lxxiii/lxxiv)

The existence of the strait was largely disproved by the voyages of Flinders and Baudin, but the inland sea and the Great River persisted until late in the 19^th century. Sir Joseph Banks had fostered the concept of the Great River: 'It is impossible to conceive that such a body of land, as large as all Europe, does not produce vast rivers, capable of being navigated into the heart of the interior…' (Letter to the Colonial Office 15 May 1798, quoted in Cumpston The inland sea and the great river page 56). Sturt solved the riddle of the western flowing rivers of New South Wales in his expeditions of 1828-30, but still believed that there was an inland sea. His expedition of 1844-46 didn't find it, but he still believed it was there. Later explorers would continue the search. In 1857 Governor MacDonnell was reporting to the Colonial Office on the work of exploration to date and still believed an inland sea was probable. (Cumpston page 141).

Philip Parker King in his surveys of the northern Australian coast between 1818 and 1822 had searched for the mouth of the supposed Great River and didn't find it; Wickham and Stokes didn't in their surveys of 1837 and 1843. It continued to be hoped for. Later explorations by Gregory, Leichhardt, Mitchell and Kennedy revealed no 'Great River'. There was only the Murray-Darling river system, and the uncertain channels of the Cooper, Diamantina and Finke rivers draining into Lake Eyre. The expeditions of Charles Sturt in the 1840s, Burke & Wills and Stuart in the 1860s had largely shown that there was no inland sea, or great river, but the concept still lingered and would not finally be dispelled until late in the 19^th century. 

Edward Eyre was one explorer who did not believe in the inland sea: 'I have never met with the slightest circumstance to lead me to imagine that there should be an inland sea, still less a deep navigable one, and having an outer communication with the ocean. I can readily suppose, and in fact, I do so believe, that a considerable portion of the interior consists of the bed or basins of salt lakes or swamps, as Lake Torrens, and some of which might be of great extent. I think also, that these alternate with sandy deserts, and that probably at intervals, there are many isolated ranges like the Gawler Range; and which, perhaps, even in some places may form a connection of links across the continent…' Eyre's deduction would later be shown to be accurate.

In one sense however the hypothesis of an inland sea had been correct: the Great Artesian Basin lying beneath much of South Australia, New South Wales and Queensland could be said to constitute an inland sea, albeit underground. And once, 100 million years ago, much of central Australia lay beneath the waters of the sea: the large saltpans of central Australia, and fossils found there are testaments to this.

Further reading:

Cumpston, JHL. The inland sea and the great river: the story of Australian exploration, Sydney, Angus and Robertson, 1964

Flannery, Tim. Australia's inland sea, Sydney: Harcourt Brace Jovanovich, c1992

Flinders, Matthew. A voyage to Terra Australis, Adelaide, Libraries Board of SA, 1966