A sample text widget

Etiam pulvinar consectetur dolor sed malesuada. Ut convallis euismod dolor nec pretium. Nunc ut tristique massa.

Nam sodales mi vitae dolor ullamcorper et vulputate enim accumsan. Morbi orci magna, tincidunt vitae molestie nec, molestie at mi. Nulla nulla lorem, suscipit in posuere in, interdum non magna.

Volcanoes, Rivers and Landscapes

The scenic landscapes of the Queensland New South Wales border region are the result of mountain building by volcanoes and erosion by several major river systems (rock cycle).

National parks gazetted over these landscapes with their graded walking tracks allow easy access to these scenic landscapes.

The Landscapes

Mt Warning and Tweed Valley

Mt Warning and Tweed Valley

Google Earth view of Mt Warning

Google Earth view of Mt Warning

Included in this blog are the landscapes of the Lamington and Springbrook plateaus, Tambourine Mountain and Burleigh Heads in Queensland, and the Border Range/Nightcap Range in New South Wales.

The landscapes were formed by the eruptions 23 million years ago of the Tweed Volcano centred on Mt Warning, and from various side vents on its slopes. Subsequent erosion (dissection) of the slopes by several rivers developed the present rugged terrain of plateaus, valleys, spurs and waterfalls

Building the Landscapes The relatively quiet eruptions of the Tweed Volcano discharged free-flowing basalt lava that spread over large areas to build up a gently sloping cone (shield volcano). The vent of this volcano remains as Mt Warning, a volcanic plug surrounded by an erosion caldera (original volcanic vent expanded through erosion by tributaries of the Tweed River).

Remnants of the Tweed Volcano’s gently sloping sides can be seen today by looking west from Currumbin Estuary to the Springbrook plateau and also from the Coolangatta Airport.

Slope of the Mt Warning Shield Volcano

Slope of the Mt Warning Shield Volcano

The Tweed Volcano, estimated height 2000 metres, inundated large areas of the older landscape. The lava flows were wide-spread, extending to: Tambourine Mountain in the North; Burleigh heads, Point Danger and Fingal to the east; Lismore in the South; and Mt Lindsay in the west. A Google Earth view of Mt Warning shows the remnants of the Tweed Volcano and its extent.

Side vents on the main volcano (Egg Rock and Charraboomba Rock at Binna Burra, and Pages Pinnacle at Springbrook) emitted a more viscous or sticky lava (Rhyolite) resulting in less extensive flows (Binna Burra and Springbrook Ryholites). Eruptions from these vents were gas–charged with violent explosions (pyroclasitc eruptions) accompanying the emission of lava. Ejected material included rock pieces of various sizes, which became welded together to form Breccia, and ash clouds whose fine particles became consolidated (compacted) to form tuffs.

Rock Sequences

The Binna Burra section of Lamington National Park allows the best views of the rock sequences. On the drive up to Binna Burra from Canungra the sequence is as follows –

  •  The top of the earliest basaltic flows from the Tweed volcano can be seen as the Beechmont Plateau (Beechmont basalts on the left across a valley just before the Beechmont roundabout).
  • Moving up the sequence are the Binna Burra Rhyolites at the level of the Information Centre just before the climb up to Binna Burra (not visible from the road, best seen from Rosin’s Lookout (turn left at the Beechmont roundabout an travel about 1.5 klms towards Nerang) and Bell Bird Lookout.

Rosin’s Lookout presents a splendid view up the Numinbah Valley through the Numinbah Gap to Mt Warning in the centre of the erosion caldera. On either side of the valley the steep cliffs of the Binna Burra and Springbrook rhyolites are clearly visible. Springbrook is to the east with Turtle rock and the northern end of Ships Stern on the west. The scenic drive through the Numinbah Valley provides closer views of these ryholitic escarpments.

  • The final flows (Hobwee Basalt) making up much of the Lamington and Springbrook Plateaus and overlie the Binna Burra and Springbrook Rhyolites. Evidence of this flow is visible in the road cuttings from the Information Centre up to Binna Burra as black, fine grained basalt rocks and red soils.
  • Pyroclastic rock sequences (by time) from the eruptions visible at Binna Burra include ash flow tuffs resulting from ash and gas flows close to the ground down the slope of the volcano followed by beds of air fall tuffs (Swimming Pool Track, Bell Bird Lookout), rhyolite with evidence of flow banding, breccia and finally air fall tuffs (Caves Circuit, Bell Bird Lookout).

In general the basaltic flows gave rise to deep fertile red soils that support closed forests (e.g. subtropical rainforest) and rhyolitic flows to poorer soils that support open forests (e.g. eucalypt forests and heathland).

Carving the landscapes – Major River Systems

The rugged beauty of the Lamington, Springbrook and Border Ranges areas is the result of the forces of weathering and erosion on the flanks of the Tweed Volcano by a number of rivers as follows –

  • Tweed River to the south east exposing the core of the volcano (Mt Warning) and producing the Tweed Valley;
  • Currumbin and Tallebudgera creeks to the north east producing the Currumbin and Tallebudgera valleys;
  • Nerang River to the north producing the Numinbah Valley;
  • Coomera River and Canungra Creek to the north forming the Coomera and Canungra valleys; and
  • Albert River, Christmas and Running Creek valleys to the West.
Caldera of the Tweed Volcano

Caldera of the Tweed Volcano

The Scenic Tweed Drive through the Border Ranges National Park follows the rim of the Caldera. The Pinnacle Lookout provides commanding views  of the Tweed Valley and Mt Warning.  the Pinnacle is the prominent projection to the left of centre in the above Photograph.

 Forests

Antarctic Beech in Cool Temperate Rainforest

Cool Temperate Rainforest

The scenic beauty of the landscape is enhanced by their climatic complexity. They lie within the sub-tropical–warm temperate transitional zone (McPherson-Macleay Overlap) displaying a mixture of habitats with sub tropical and temperate elements.

The area’s volcanic history and subsequent erosion (dissection) by a number of river systems provide excellent examples of the interactions of climate, soils and topography on biological communities. These interactions have resulted in a diversity of habitats within the Park including complex subtropical rainforest, warm temperate rainforest, cool temperate rainforest, eucalypt forests and mallee heathlands. The cool temperate rainforests occur in areas above 900 metres that receive abundant rainfall. They are relicts of the last ice age.

The area forms part of the World Heritage listed Gondwana rainforests in New South Wales and Southern Queensland. The included forests are remnants of subtropical rainforests with elements of warm and cool temperate forests thought to be examples of the more luxurious plant communities that existed over a wide area of Australia when it was part of Gondwana.

Instructive Walks

The rock formations are best exposed in the Binna Burra Section of the Lamington National Park. The following national park walks provide excellent views of the rock sequences and forest transitions –

  • The Caves Circuit [5k]
  • Bell bird Lookout [2k return]
  • Lower Bell Bird track [9k return]
  • Biby Lookout on The Coomera Circuit [approximately 20k return]
  • Lookouts from the Ships Stern Circuit [19k]
  • Daves Creek Circuit [13k]

Of these the best for rock sequences are Bell Bird Lookout and the Caves Circuit. From Bell Bird Lookout the side of Ships Stern shows a deep bed of tuff overlain by a deeper bed of Binna Burra Rhyolite.  Turtle Rock at the northern end of Ships Stern is almost entirely tuff.

Some of the rock sequences, including Egg Rock, can be seen on the scenic drive up the Numinbah Valley, which passes between the Springbrook Plateau on the east and Ships Stern on the west.

The Daves Creek Circuit is one of the best walks available to see the effects of soils, elevation and aspect on habitats. The transition is subtropical rainforest, warm temperate rainforest, cool temperate rainforest, eucalypt forest and malle heathland.

Reference: Detailed discussions of the rocks and rock sequences on walks can be found in the Book by Warwick Willlmott 2004 (see the References page of this blog).

The Rocks

The rock types visible on walks include —

Basalt: Black to dark grey, fine grained volcanic rock with few crystals and no evidence of flow bands. In some areas such as the tops of flows the basalt contains holes or vesicles which are gas bubbles trapped as the larva cooled rapidly. Basaltic lava is free flowing, spreading across large areas and generally is produced from relatively quiet eruptions. Soils developed from basalt tend to be fertile and support tall closed forests on the plateau and chocolate or black soils on the slopes where the forest may be more open.

Rhyolite: Very fine grained, light cream, buff or pink rock resulting from a viscous or sticky lava often ejected with violent explosions (pyroclastic events) from the volcanic vent. Other rocks associated with the violent activity are breccia and tuffs.

Because of the high viscosity of ryholitic lava (like cold treacle) its flow is less extensive than basaltic lava and its beds may exhibit flow bands. Deep flows occur at Binna Burra (Bell Bird Lookout, Ships Stern, Coomera Falls) and Springbrook.

Perlite: a glassy, dark, almost black rock formed at the upper and lower layers of Rhyolite where rapid cooling has occurred. In some cases perlite exists in rhyolite flows as rounded spherulites (Caves Circuit, Lower Bell Bird circuit).

Tuff: Pyroclastic rocks formed from consolidation (compaction) of fine material ejected as clouds during volcanic explosions (Swimming Pool track, Bell Bird Lookout, Turtle Rock, Ships Stern). Because of the fine nature of the particles they are carried on the wind and deposited further from the vent than heavier lumps of rock that form volcanic bombs or those welded into breccia.

Breccia: Relatively larger pyroclastic rocks formed by consolidation of larger particles ejected from the volcanic vent during violent eruptions (Caves Circuit).

Rhyolite, breccia and tuff weather to relatively infertile soils supporting eucalypt forests and heath lands.

(Adapted from Warwick Willmott, 1992: p10. Rocks and Landscapes of the Gold Coast Hinterland, Expanded second Edition)

1 comment to Volcanoes, Rivers and Landscapes

Leave a Reply

You can use these HTML tags

<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>