Australia: The Land Where Time Began

A biography of the Australian continent 

One of the first signs of the break between Australia and Antarctica began about 165 million years ago with the stretching of the crust between the 2 continents where the eventual break was to occur. Dolerite magma filled the cracks in the underside of the crust and its sandstone covering in the form of dykes, sills and sheets. The colonnade-like appearance of the dolerite pillars resulted from the shrinkage cracks that formed as the magma cooled from the top down. When the covering of sandstone was eroded away the dolerite was exposed in the form of the Acropolis, Mt Geryon, etc. The present form of the Acropolis resulted from some modification of the original formation by an ice cap that covered it about 15,000 years ago.

At the head of the Narcissus River Valley the Acropolis, together with other dolerite mountains, Mt Geryon and Mt Massif, all part of the Du Cane Range, form an arc-shaped barrier. These and other peaks of the Du Cane Range are within the Cradle Mountain-Lake St Claire National Park.

The Acropolis had previously been given the unofficial name of the Porcupine. Mt Geryon was previously called the Rifle Sight, Precipice Mountain. Mt Geryon was also called Tarperian Rock for a time until its present name became established.

Sources & Further reading

1. Helen Grasswill & Reg Morrison, Australia, a Timeless Grandeur, Lansdowne, 1981

Ranges