Palynology and Historical Ecology of Some Cave Excavations in the Australian Nullarbor

Abstract

Palynological information from deposits associated with three archaeological sites on the Nullarbor is documented and interpreted in relation to likely environ- mental changes and aboriginal prehistory in the region. Deposits from two excavations near Madura have been dated at 8000-9000 years before present (B.P.), whilst a third deposit located near Eucla is probably 27,000-28,000 years B.P. Palynologically, the key interest centres on a demon- strated reciprocal relationship between the Myrtaceae (M) and chenopod type (C) grains in the pollen spectra from these sites, and the fact that the respective pollen ratios (M/C) of present surface deposits reflect the relative abundance of these two floristic groups in the modern regional vegetation. Evidence from the pollen spectra of the Eucla profile suggests that some 18,000 years B.P., when the sea was at its last glaciation low level of 90 m below the present level, the treeless plain extended south of its position today to this district. A marked increase in mallee shrub cover, associated with evidence of a rising sea level, occurred about 5000-9000 years B.P., and from this time to the present, the cover has been maintained or increased slightly. Unlike those of Eucla, both the Madura pollen profiles provide evidence of a marked decline in the mallee scrub cover, from 5000-6000 B.P. to the present. A substantial increase in the density of artifacts is regarded as possible evidence of an increased aboriginal population in all three profiles, about 4000-6000 B.P. From the evidence available, it appears that man and his uninhibited use of fire may have been largely responsible for the relative decline in mallee scrub near Madura where regeneration is restricted by a lower rainfall, whereas at Eucla a slightly higher rainfall regime allowed a more continuously effective regeneration of this vegetation type.