Vegetation History and Water Fluctuations at Lake Leake, South-Eastern South Australia. II. 50 000 B.P. To 10 000 B.P

Abstract

A drill core from Lake Leake contains a sedimentary sequence extending from about 50,000 B.P. until the present. This paper discusses the results of the pollen analyses and six radiocarbon dates which span the period from about 50,000 until about 10,000 B.P. There are core sections which yielded low numbers of pollen and thus there are gaps in the vegetation record. It is suggested that open eucalypt woodland was replaced by eucalypt woodland with heath at about 50,000 B.P. and remained until about 39,000 B.P. Open woodland then returned but was replaced by eucalypt woodland with heath by 38,000 B.P. Some time after 35,000 B.P., open eucalypt woodland conditions returned and persisted until near 10,000 B.P. when Casuarina stricta migrated into the area. Through- out the period in question the climate was drier than it has been in the last 10,000 radiocarbon years. There were wet periods about 50,000 and 39,000 B.P. and from 38,000 to 35,000 B.P. The character of the sediments and the relative amounts of pollen preserved suggest that conditions were relatively dry from 50,000 to 39,000 B.P. and from after 35,000 until near 10,000 B.P.

The lake was driest during the period of the last glaciation but the presence of eucalypt pollen is interpreted as indicating that the average annual minimum temperature was above 10°C and the average annual rainfall was above 20-25 cm.