Australia: The Land Where Time Began

A biography of the Australian continent 

Terminal Miocene Event About 6 Ma 

At the transition from the Miocene to Pliocene the climate cooled and became much drier, and more seasonal, as in the case at the present. Antarctica became completely ice bound, being covered by permanent glaciers. An abrupt change saw the formation of the Arctic ice cap about 3 million years ago as indicated by an abrupt shift of oxygen isotope ratios, and in the North Pacific and North Atlantic, the presence of ice-rafted cobbles. It is believed that mid-latitude glaciation was under way by the end of the Epoch.

It was during this event that the West Antarctic ice cap became fully formed and ice linked the now glaciated west with the glaciated east. The total volume of ice cover on Antarctica was higher than at the present, having a very large effect on the global sea levels. The locking up of so much ice lowered the sea level enough to strand the Mediterranean Sea. During this event there were a number of phases, warmer phases alternating with cooler phases. The result was that the Mediterranean filled and evaporated several time before the end of the event. The result is that it has been estimated that the repeated evaporation of such a large water body accumulated salt deposits beneath the Mediterranean totaling an estimated million cubic kilometres of halite and gypsum.

The removal of so much salt is believed to have reduced the ocean's salinity by 6 %.

These discoveries were made long after Darwin's death, so when he referred to this event he must have been referring to the onset of the period of cooling.

Sources & Further reading

  1. Mary E White, After the Greening, The Browning of Australia, Kangaroo Press, 1994
  2. Mary E. White, The Nature of Hidden Worlds, Reed, 1993
Author: M. H. Monroe
Last updated 19/04/2011


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