History of the Brisbane Ranges
Ranges stretch from Baccus Marsh in the north to Maude in the south,
and have a maximum elevation of 440 metres. Steep valleys and Gorges
dissect the eastern part of the Park, while the western portion of the
Park is more undulating and more easily accessible.
Ranges mainly consist of sedimentary rocks of early to mid Ordovician
age (505 million years ago). These sediments were deposited during a
time when the first fish were evolving and shelled organisms lived
throughout the seas and oceans. At this time, the sea was much higher
than the present level and most of Southern Victoria was submerged. The
sediments were deposited by underwater avalanches (Turbidites) that
fall due to gravity from the continental shelf to the ocean floor.
These avalanches deposited hundreds of metres of sand, silt and mud on
the ocean floor.
As deposition of sediments continued over time,
the underlying Ordovician sands, silts and muds were compressed forming
sandstone, siltstone and shale.
The next major event in time that
resulted in the Ranges' current day appearance occurred about 380
million years ago during the late Devonian, a time when the first
amphibians were first venturing from the sea to the land. During this
time, the earth experienced extensive plate movement that compressed,
buckled and folded the Ordovician sediments. At the same time molten
magma melted through the sediments to the east of the Ranges. The magma
soon cooled and has since been exposed as granite, forming the You
Yangs and the Anakies to the east and the site of the Fairy Park and
Dog Rocks to the south-east. The compression by the plate movements and
the heat from the molten magma metamorphosed some of the shale in the
Ranges to slate, which has since been quarried in the north-east corner
of the Park.
At the conclusion of the Devonian, the world
experienced a time of cooling, which led to the development of ice caps
and a lowering in the sea level. This global cooling was not sudden, as
it occurred over a period of 150 million years, during which more
sediment was deposited upon the folded Ordovician rocks.
world was now in the Mesozoic (200 million years ago), a time when
dinosaurs roamed the land and the first birds and animals emerged. It
was at this time that the super continent, Gondwana separated and
Australia took on its present shape as an island continent. The sea
level receded and the overlaying sediments were eroded away, exposing
the You Yangs granite as an island in a shallow sea.
The next 195
million years were "relatively uneventful", except for the extinction
of the dinosaurs, the development of mammals and the continuing fall in
That was until about 4 million years ago
(Pliocene-Pleistocene) when Central Victoria experienced considerable
faulting. The Rowsley, Hanover and Meredith Faults uplifted the
Brisbane Ranges above the plains to the east. During this time, Western
Victoria was volcanically alive, as lava flowed from Mt Anakie,
covering the Werribee Plains and areas towards Geelong, and lava from
Mt Wallace covered the plains to the north-west.
extinction of the volcanoes, the Brisbane Ranges have continually been
eroded by wind and water systems such as Little River and Stony Creek,
cutting steep sided valleys into the Ordovician rocks along their
winding course. The eroded Ordovician rocks and overlying sediments
have been deposited as river sands at the base of the Ranges and
dispersed out over the basalt plain.
It is through all of the
above processes, which originated over 500 million years ago that we
are able to enjoy the magnificent panoramic views, the beautiful
gorges, and rich flora and fauna diversity of what we now know as the
Brisbane Ranges National Park.