The evolution of Australian island geographies and the emergence and persistence of Indigenous maritime cultures

Abstract

Australia was first peopled by maritime voyagers who intentionally crossed from Indonesia using watercraft 65,000 years ago. Despite this, the Holocene archaeological record suggests that many Australian islands were abandoned for several thousand years after separation from the mainland, and only visited again in the last few thousand years. The implication is that coastal peoples reintroduced watercraft into their maritime repertoire only in the recent past. Since first-peopling, sea levels have fluctuated over 120 m, transforming the coastlines and offshore island geographies. In this study, we assess Australia's offshore islands over the range of past sea levels, to discover that most of the Australian coastline has far more islands now than at any time in the human past. Australia's island-rich coastlines emerged with the high sea levels of the late Holocene. The existing island geographies of the Pilbara, the Great Barrier Reef, the Bass Strait and the Rottnest Shelf have no Pleistocene equivalents, meaning coastal peoples encountered new maritime opportunities as modern sea level was established (c. 7 ka). We present regional time series, and detailed paleogeographical maps of these changes, produced by a fully reproducible GIS method. We contextualise this in a review of Australian island archaeology, and demonstrate that key exceptions to this geographical trend are the Kimberley and the Torres Strait – which have evidence for earlier and longer continuous island sequences. These exceptions provided the opportunity for regional persistence of Pleistocene seafaring.