Australia: The Land Where Time Began

A biography of the Australian continent 

Pollen Core ODP820, marine sediment core 45 km off Cairns - The moist tropics

The pollen in cores from this site are believed to have originated in a large area of adjacent coastal areas and ranges, being carried to their marine location by freshwater streams flowing to the sea. The period covered by the cores from this site is from about 1.5 Ma to the present. A general description is included in the Kershaw et al. (19930, and they go into more detail in Moss & Kershaw (2000) for the period of the last 200,000 years. Their results indicate that rainforest was dominant for most of the last 1.5 million years, with abundant conifers. Casuarina dominated Sclerophyll forests were present, with banksias and acacias, with only small numbers of eucalypts. There were also freshwater aquatic plants such as grasses, sedges and ferns, an episodically, mangroves. This assumed to indicate high sea levels.

After 200,000 BP there was a change of vegetation in which there was an increase in eucalypt dominated vegetation and the retreat of rainforest conifers. A difference between this site and Lynchs Crater is that at this site there were 2 instances of vegetation change, one each of the 2 glacial phases. Throughout the LGM Poaceae continued to increase as the sclerophyll vegetation declined, suggesting the regional spread of local grasslands or savannas. Charcoal was present throughout the period covered by the cores, increasing near the end of each glacial phase.

 

Sites where pollen has been recovered in cores

Sources & Further reading

  1. Mary E. White, The Greening of Gondwana, the 400 Million Year story of Australian Plants, Reed, 1994
  2. Chris Johnson, Australia's Mammal Extinctions, a 50,000 year history, Cambridge University Press, 2006

 

 

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                                                                                           Author: M.H.Monroe  Email: admin@austhrutime.com     Sources & Further reading