Riversleigh Fossil Fields

Location
Riversleigh is a cattle station on the Gregory River, situated 250 km north-west of Mount Isa and 75 km south-east of Lawn Hill National Park, and covers 3108 square km. The Riversleigh fossil vertebrate deposits are among the richest and most extensive in the world and for this reason in 1992 the deposits were included in an extension to the Lawn Hill National Park.

The Fossil Deposits
The deposits at Riversleigh are found over 40-60 square km and represent three different periods in time. Most are in light coloured limestone 10-25 million years old that overlie much older, darker limestones. Another time period is represented at Rackhams Roost where the bones of carnivorous bats and the creatures they caught and ate 3.5 million years ago have been found in the remnants of an ancient cave high above the Gregory River. A third time period is preserved in old river terraces where the remains of animals that lived and died in and along the Gregory River some 50,000 years ago have been found.

The Riversleigh Landscape
The most common rocks in the area are 530 million year old limestones formed when shallow inland seas covered vast areas of Australia. Hiding among the hills and ridges are younger limestones formed in freshwater pools and lakes, around 10 to 25 million years ago, long after the seas receded.

These younger rocks contain the fossils for which Riversleigh is famous. Since 1983 the beautifully preserved remains of thousands of ancient inhabitants of northern Australia, including giant pythons, carnivorous kangaroos and marsupial lions, have been recovered from those rocks and are adding immeasurably to our developing knowledge of the history of our continent and its animals.