Australia: The Land Where Time Began

A biography of the Australian continent 

Landscape of Colonisation

At 45 ± 5 ka the first humans are believed to have entered the interior. The interior is indicated by most records from the Quaternary to have been significantly more arid than at any stage during the last interglacial (Hesse et al., 2004). Early in MIS 3 people moving into the interior would have encountered extensive deserts and drylands, with grasslands of xeric vegetation, and the dryland conifer Callitris dominating chenopod shrublands and open woodlands (van der Kaars & De Deckker, 2002; Hesse et al., 2004; Smith, 2009b). Around the Puritjarra archaeological site, Central Australia, at 45 ka, the vegetation was an arid, open shrubland or herbland, with little grass and isolated trees in a landscape that was already being impacted by intensified aridity (Smith, 2009b). By 70-60 ka continental dunefields had been widely reactivated and at this time greater dust fluxes indicated land surface instability was increasing.

Smith suggests that prior to the first movements of humans into the desert most palaeolakes had dried up. At Lake Eyre the last deepwater phase ended 65,000-60,000 years ago (Magee & Miller, 1998), which coincided with a drop in fluvial activity in the associated river systems, as well as with the collapse of the Katapiri fauna. Smith claims Genyornis was the only species of megafauna that had not gone extinct across the interior at the time      when humans first entered the desert.

The freshwater lakes on the margins of the desert were exceptions to this pattern. Rivers and lakes in the Darling Basin and the Willandra region, in the southern section of the arid zone, were active during MIS 3 and MIS 2 (especially between 55 ka and 15 ka, Bowler, 1998), runoff from the highlands of southeast Australia flowing into a chain of terminal lakes, of which the most famous is Lake Mungo. During MIS 3 there was also reactivation of rivers and lakes in the Lake Eyre basin, especially at Lake Frome – though this appears to have had little impact in Central Australia or the Western Desert. Along Cooper Creek, and possibly also along other channels in the Georgina-Diamantina system, there were strong flows that were episodic (Nanson et al., 2008: 119).  As regional dunefields of the Tirari and Strzelecki Deserts were also active at this time (Fitzsimmons, Rhodes, Magee et al., 2007), during the MIS 3 the picture is of an environment that is arid with high submillennial variability as well as strong seasonality. It is suggested by this is that the channels that feed Lake Eyre, Warburton River, Cooper Creek and Kallakoopah Creek, functioned as classic arid rivers: with channels that are mostly dry and with saline water outcropping in places, though reactivated periodically during unusually wet years, when they carry large flows to Lake Eyre. During MIS 3 Lake Eyre filled again, forming a saline body of water that was no larger than floods that occur periodically at the present.

According to Smith there is not much evidence in support of the proposition that the early occupation of the desert areas of Australia selectively relied on the presence of lacustrine or riverine resources, or that the first occupation of the deserts occurred at the time of a ‘lacustral phase’ (Hiscock & Wallace, 2005). In the Darling and Willandra regions human groups had access to active river and palaeolake systems in the Pleistocene. Further inland, along the channels and back-swamps of Cooper Creek and the Warburton River, it is likely that riverine resources were less reliable and became increasingly seasonal with distance along the channels. As people moved further inland they would have encountered an interior of open arid landscapes of dunes and saltlakes, landscapes that lacked coordinated river systems.

The interior was an arid landscape that had been shaped by many millennia of selective pressure by the time the first colonists moved into it, though Smith suggests its ecological structure and controls may have been subtly different from those of the Australian deserts of the present. Although the Australian monsoon had weakened substantially by 45 ka, it is significant that it remained stronger than it is at the present. It is likely that potable water may have been widely available in claypans, small soakages, waterholes and springs as a result of lower evaporation and a more active monsoon. The colonists would have gained greater flexibility in the annual and seasonal subsistence travels than at present, by these small water bodies, which would allow more efficient access to   the plant and animal resources of these drylands. For hunter-gatherers in the desert mobility is crucial and Smith suggests these small water bodies would have provided an effective way of ‘stepping through’ these unique landscapes.

The old floodplains and dry lake beds would have been littered with the bones of megafauna, as are still present in a few places, such as Lake Callabonna, as the early colonists moved into the interior of the continent. The Thirrari, Diyari and Wangkangurru people incorporated these animals into their cosmology, associating them with Kardimarkara (the Rainbow Serpent), an immense creative being that was closely associated with rain and waterholes. Mick McLean Irinjili described how the old people had found big bones in a waterhole and covered them over, ‘out of respect and pity’.

Sources & Further reading

Smith, Mike, 2013, The Archaeology of Australia’s Deserts, Cambridge University Press