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As you enjoy the immense natural beauty of the rainforests on the Embrace Australia's Gondwana Rainforests tour, it's worth remembering how these magnificent forests were formed and preserved for future generations.
December 2009
The lands contained within the Gondwana Rainforests of Australia contain remnants of the great rainforests that once covered the entire continent of Australia.
These reserves feature striking vertical cliffs, the world’s best preserved eroded volcanic craters, wild rivers and many impressive high waterfalls.
An outstanding record of flowering plants, songbirds and rare or threatened animals of ancient lineage show that these reserves have played a significant role in providing refuge to species for millions of years.
In 1986, a number of rainforest reserves located on the Great Escarpment of eastern New South Wales, known as the Australian East Coast Sub-tropical and Temperate Rainforest Parks, were inscribed on the UN World Heritage list for their outstanding natural universal values:
- as an outstanding example representing major stages of the earth's evolutionary history
- as an outstanding example representing significant ongoing geological processes and biological evolution
- containing important and significant habitats for the in situ conservation of biological diversity.
Large extensions to the area, including reserves in southeast Queensland, were listed in 1994 as Central Eastern Rainforest Reserves (Australia); in 2007 the name was changed to Gondwana Rainforests of Australia to better reflect the values of the property.
The current listing includes 50 separate reserves located between Newcastle and Brisbane, managed principally by four different agencies: NSW National Parks and Wildlife Service, Queensland Parks and Wildlife Service, State Forests of NSW and the Queensland Department of Natural Resources.
The total area of Gondwana Rainforests of Australia is 366,507 hectares ; 59,223 ha in Queensland and 307,284 ha in New South Wales.
Rainforests occur in New South Wales and south east Queensland as discontinuous patches surrounded by fire-prone eucalypt forest and agricultural lands. These patches range in size from tiny gully stands to lush forests covering large valleys and ranges. The Gondwana Rainforests include the most extensive areas of subtropical rainforest in the world, large areas of warm temperate rainforest and nearly all of the Antarctic beech cool temperate rainforest.
Rainforest once covered most of the ancient southern supercontinent Gondwana and remains the most ancient type of vegetation in Australia. The Gondwana Rainforests provide an interesting living link with the evolution of Australia. Few places on earth contain so many plants and animals which remain relatively unchanged from their ancestors in the fossil record. Some of the oldest elements of the world's ferns and conifers are found here and there is a concentration of primitive plant families that are direct links with the birth and spread of flowering plants over 100 million years ago.
A range of geological and environmental influences in the Gondwana Rainforests determine where forest communities grow. This process has occurred over millions of years and will continue to change the forest mosaic into the future.
High waterfalls crashing into steep gorges are spectacular examples of the important ongoing natural process of erosion. Erosion by coastal rivers created the Great Escarpment and the steep-sided “caldera” of the Tweed Valley surrounding Mount Warning. This towering mountain was once the buried plug of an ancient vast volcano. Today, rainforest grows on the fertile, well watered soils that remain.
The evolution of new species is encouraged by the natural separation and isolation of rainforest stands. Many plants and animals found in the World Heritage property are locally restricted to a few sites or occur in widely separated populations.
Australia was once part of a much larger land mass called Gondwana which included the modern continents of Africa, South America, Antarctica and India. Proof of this has been provided by the discovery of many of the same ancient plants and animals in fossil beds dispersed throughout parts of all of these present day continents.
About 120 million years ago, Gondwana began to break up. Connections with Africa and South America were broken about 100 million years ago; about 80 million years ago, New Zealand and New Caledonia broke away from the eastern edge of the Australian plate; finally, about 50 million years ago, Australia separated from Antarctica and began moving northwards. For 35 million years it was totally isolated from all other land masses until it collided with the Asian plate.
Rainforests are some of the most significant ecosystems on earth. They are relics of vegetation types which were once much more widespread – fossil pollens indicate that most of Australia was covered by closed forests some 50 to 100 million years ago. All of Australia's unique marsupials and most of its other animals originated in rainforest ecosystems.
Although rainforests cover only about 0.3 per cent of Australia, they contain about half of all Australian plant families and about a third of Australia's mammal and bird species. The Gondwana Rainforests have an extremely high conservation value and provide habitat for more than 200 rare or threatened plant and animal species. The distributional limits of several species and many centres of species diversity occur in the Gondwana Rainforests. The Border Group is a particularly rich area, with the highest concentration of frog, snake, bird and marsupial species in Australia.
The Properties of the Gondwana Rainforests of Australia
The Gondwana Rainforests of Australia are actually composed of a series of eight distinct groupings of parks and reserves distributed between Newcastle and Brisbane, united by the common story they tell of Australia's unique and evolving rainforests.
Barrington Group
Barrington Tops National Park contains an unsurpassed mosaic of eucalypt forests and rainforest types, plus subalpine woodlands, swamps and grasslands.
New England Group
Dorrigo National Park includes majestic subtropical rainforest and enchanting waterfalls as well as the Dorrigo Rainforest Centre, a major interpretation centre for the Gondwana Rainforests of Australia. Point Lookout in New England National Park provides unforgettable panoramas over forested wilderness.
Hastings-Macleay Group
The spectacular gorges of Oxley Wild Rivers National Park can be viewed from lookouts, camping and picnic areas on the edge of the New England Tablelands. Moister rainforest-clad mountains and gullies are found in Werrikimbe National Park.
Illuka Group
Illuka Nature Reserve contains the largest remaining stand of littoral rainforest in NSW, an important and fragile patch of rainforest by the sea.
Gibraltar Range Group
A wild region of tall trees and clear waters, Washpool National Park is the largest rainforest wilderness in NSW. Neighbouring Gibraltar Range National Park is renowned for spring-time wildflower displays, rocky outcrops and panoramic views.
Main Range Group
Main Range National Park contains unusual forms of subtropical rainforest which provide habitat for rare ground-dwelling birds such as Albert's lyrebird and the eastern bristlebird.
Focal Peak Group
From the rugged volcanic peaks of Mount Barney National Park through Tooloom National Park and Mallanganee National Park to the lush lowland subtropical rainforest of the Murray Scrub in Toonumbar National Park, these rainforests abound in fruit-eating birds such as fruit doves, bowerbirds and the rare Coxen's fig parrot.
Along with these National Parks, the Focal Peak Group were declared inside the Mount Nothofagus Flora Reserve and the Richmond Range National Park in the 1994 World Heritage re-listing when these estates were still state forests. World Heritage areas are also declared inside Mount Clunie National Park and Koreelah National Park.
Border Group
Springbrook National Park features panoramic views over the Gold Coast and northern NSW from walks through subtropical and cool temperate rainforest. Lamington National Park protects the largest remaining tract of undisturbed subtropical rainforest.
Mount Warning National Park protects the diverse rainforest communities which clothe this rugged mountain peak. Walks, scenic drives, dramatic lookouts and visitor facilities are provided in Border Ranges National Park, whilst Nightcap National Park provides excellent day facilities and walking tracks.
The Caldera of the Tweed Volcano
To vulcanologists a “caldera” is a bowl shaped depression caused by the collapse or erosion of a volcanic cone.
The huge size of the Tweed Valley, the caldera of the Mt Warning shield volcano, gives us an inkling of what a monster it was. Today the caldera valley is over 1,000 metres deep with a diameter of over forty kilometres, making it even larger than the famous Ngorongoro Crater in Tanzania.
It is one of the world's great natural wonders and one of the few places where the erosion process can be seen through to the underlying pre-volcanic sedimentary and metamorphic rocks, providing enthusiasts with a wonderful opportunity to test their knowledge of geological processes.
Moving over a hotspot in the earth's crust about 23 million years ago, the volcano erupted through the layers of the “Brisbane Metamorphics Series” (250-500 million years old) and spread out over the “Clarence-Moreton Basin” sedimentary floor (laid down 135-200 million years ago).
When the volcano finished its eruptions about 3 million years later, the volcano had risen to a height of over two kilometres. Layers of ash and lava had been deposited over its outward slopes, to a diameter of about 100 kilometres.
This spread the volcano out over an area from Byron Bay in the southeast and Lismore in the southwest to Mount Tamborine in Queensland to the north.
Over the past 20 million years the vast majority of the material ejected by this long series of eruptions has been eroded away by time and the effect of the many creeks and tributaries that feed the Tweed River, winding its way across the valley floor and eventually entering the ocean at Tweed Heads.
What remains is still mighty impressive. The central magma plug of Mt Warning and a system of ring dykes (extremely hard rock formations) have resisted erosion and dominate the valley landscape, especially in and around the township of Murwillumbah.
The rim of the caldera has been protected by a cap of very hard basaltic rock, forming a virtual semi circle of vertical cliffs around the western side of Mt Warning – increasingly known by its aboriginal name of Wollumbin – which now stands at just over 1,100 meters tall.
Being so high and so far east on the Australian coast, it is the first peak on the mainland in Australia to be touched by the rising sun at the Autumn and Spring Equinox.
Sugar cane, cattle and dairy farming make use of much of the rich post-glacial alluvial deposits on the caldera valley floor while the heights are protected in their natural state by their inaccessibility and World Heritage listing of several National Parks and Reserves in the region.
Sources:
Department of Environment, Water, Heritage and the Arts, “Gondwana Rainforests of Australia” (Online brochure) - www.environment.gov.au/heritage/places/world/gondwana/index.html
Big Volcano Visitor Guide - www.bigvolcano.com.au
Wet Tropics Management Authority - www.wettropics.gov.au
The Big Scrub
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