Byron Bay is part of a unique Australian volcanic region called the Tweed Volcanic Region.  20 million years ago, the Mt. Warning Shield Volcano extended from Tamborine Mountain in the north over 100 kilometres south to Lismore, and from  Kyogle 60 kilometres to the east.  It was over two kilometres high.  The very first lava flows extended out to sea over Byron Bay and formed the present Lennox and Skennars Headlands near Ballina as they flowed down and filled an old valley.  They are seen now under the rich red soils of the Alstonville-Bangalow plateau.  On the Tweed coast they flowed down another old valley and are still seen in Fingal Headland, Point Danger and Burleigh Heads National Park.  In the north they flowed out to form Beechmont and Tamborine plateaus.  In the west they flowed to Kyogle and covered previous lava flows from the Mt. Barney Shield Volcano.

This phase was followed by rhyolite lava flows from vents at Doon Doon and Huonbrook in the south and Springbrook in the north.  This formed cliff and gorges in the Nightcap National Park and the Lamington National Park.  It can best be seen in the cliffs of Springbrook and along the Numinbah Valley.  Very violent eruptions threw out great masses of ash, glass and volcanic bombs that make up some parts of those areas.  The last phase was basalt again that now can be seen only on the very tops of the ranges above 900 metres.

Since that time, the Tweed River has eroded a large hole in the centre, called a caldera.  In the middle of this the striking spires of Mt. Warning and its smaller ring dykes stand out as a hard resistant mass.  They were plugs deep in the main vents of the volcano.  Around the caldera is a ring of precipitous escarpments that reveal all the layers of the volcanic story.  Outside them are the remains of the sloping flanks of the shield, with many long radial ridges still showing something like the original slopes.  From Tweed Heads and the southern Gold Coast, a view to the south-west shows the old surface in the profile of Springbrook.  It can be seen from the hills above Nimbin looking south-west at the Mackellar Range.  Great views over the caldera and Mt. Warning can be seen from the Blackbutts and Pinnacle Lookouts in the Border Ranges National Parks and from Best-of-All Lookout at the top of Springbrook. The remnants of the shield surface can be seen cut by streams with their gorges, waterfalls and cliff faces.  All parts of the Tweed Volcanic Region can be reached by day trips from the coast, most roads are sealed and information is available from National Parks Offices and the Tourist Information Centres.

The great shield volcano provided a refuge for hundreds of species of plants and animals that came up with Australia from Gondwana, and came in from Asia.  Its heights trapped rain-bearing winds during the long years when Australia dried out and lost most of its rainforests.  Its rich basalt soils provided new nutrients from deep in the earth..  It is now one of the most biologically diverse regions in Australia, with 125 plant species found nowhere else, over 200 bird species, 30 species of bats and more marsupial species than anywhere on Earth.  It has a relict Antarctic Beech rainforest from Gondwana, isolated but surviving, high on the misty, wet tops of the ranges.

Tweed Volcanic Region - 360 Million Years Ago to the Present Day

An environmental history of the Beaudesert, Gold Coast, Tweed, Brunswick and Richmond Region.

Compiled by Bruce Graham

Covers all stages of geology, landscape formation by erosion, climate, soils and all major forest and heath types with their animals.  Impacts of humans are dealt with.  The only book covering the Tweed Volcanic Region in this detail.. Natural sciences in easy-read format.  A4 soft cover, extensive references for serious students, index, glossary.

Available from Bruce Graham, 5 Meridian Way, Tweed Heads 2485.   bwgraham@bigpond.com    Ph. 07 5536 1441

$25 plus $7 post and packing.  Re-sellers phone for details.  Sales on invoice to schools, libraries and nice people.