Australia: The Land Where Time Began

A biography of the Australian continent 

Holocene Vegetation - Palaeoclimatic and Palaeomagnetic History, Lake Johnston, Tasmania

Some of the best subalpine rainforests in Tasmania are found in the Lake Johnston cirque. The sediments in Lake Johnston contain pollen of Lagarostrobos franklinii, that grows up to 1040 m, suggested by the authors¹ to possibly be a relict from glacial times. Rainforests of the Nothofagus-Cunninghamii-N. gunnii type, a subalpine type, developed between 9,000 and 6,000 BP, reaching a maximum at 8,700 ¹⁴C yr BP, with N. gunnii becoming more important after 6,000 ¹⁴C yr BP, and there was an increase in sclerophyll and heath components, and partial burning of the catchment occurred periodically. The climate of the Early Holocene was warmer and wetter than that of the Late Holocene. The changes of vegetation and climate are indicated by the pollen record to be similar to those indicated by the pollen records of New Zealand and Chile. According to radio carbon dates sedimentation occurred at a rate of 0.43 mm/yr, the cores being correlated by magnetic susceptibility. According to the authors¹ magnetic ages are assigned by matching with the secular variation master curve for southeastern Australia, and when these ages are adjusted by 350 years they are consistent with the ¹⁴C chronology.

Sources & Further reading

1. Anker, Sharon A., Eric A. Colhoun, Charles E. Barton, Mike Peterson, and Mike Barbetti. "Holocene Vegetation and Paleoclimatic and Paleomagnetic History from Lake Johnston, Tasmania." Quaternary Research 56, no. 2 (9// 2001): 264-74.