Download Geology of the Springbrook Plateau

Geology of the
Springbrook Plateau
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School: _______________________
Date: _________________________
Geology of the Springbrook Plateau
Student Program Booklet
First Published in 2013
by
Numinbah Valley Environmental Education Centre
1721 Nerang-Murwillumbah Rd, Numinbah Valley Q4211
All rights reserved
2013 Edition
Copyright © State of Queensland, (Department of Education, Training and Employment) 2013
Copyright protects this publication. Except for purposes permitted by the Copyright Act, reproduction by whatever means is pr ohibited. However, limited
photocopying for classroom use is permitted by educational institutions that have a license with the Copyright Agency Limited (CAL). Any inquiries should be
addressed to the Copyright Officer, Studies Directorate, Department of Education, PO Box 33, Brisbane Albert St, Q 4002
ACKNOWLEDGEMENTS
Original Concept and Program Development: Renata Machado Medeiros, Jim Rebgetz, Kees Nyssen,
Melissa Traill, Sarah White and Kate McKensie
Booklet Design and Typesetting: Kees Nyssen and Renata Machado Medeiros
Illustrations: Jason Bell
Special thanks to the geologist Warwick Willmott and to the Botanist David Jinks for sharing their knowledge with us.
Numinbah Valley Environmental Education Centre
1721 Nerang-Murwillumbah Rd, Numinbah Valley Q 4211
Ph: (07) 5533 4148 – Fx: (07) 3374 2857
Website: www.numinbaheec.eq.edu.au
Email: [email protected]
Keeping safe in the Forest
 Wear sturdy shoes, a hat and sunscreen and take water.
 Stick to the tracks to avoid trampling plants and animals
 Pick up rubbish to keep our forests clean but be careful of glass or any sharp objects
Learning Intents
Students will be working towards the following learning intents:
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Explain how rock can be changed into soil, through different types of weathering (chemical and physical/biological)
Name and recognise the difference between chemical and physical weathering
Describe the environmental conditions that prohibit (native) seed germination
Identify environmental conditions that allow introduced species to grow and survive
Identify types of igneous (extrusive) volcanic rocks and describe the processes involved in their formation
Create links between the formation and destruction of rock types and the processes involved
Evaluate the relationships in the formation and destruction of rock types
Determine the origin of rocks on the surface of the Earth
Relate processes of rock formation with the geological timescale
Identify rock types and other evidence in fieldwork locations
Identify how rocks and minerals were used by humans
Relate how the use of rocks and minerals has changed over time
Link the properties of rock with their uses by different cultures
Geological and Geomorphological History of the Region
Springbrook National Park is located on the northern flank of the extinct Tweed Volcano, a broad shield volcano
which erupted between 23 and 24 million years ago. At that time this part of the Australian crustal plate, which is
moving 7cm northwards each year, was over a ‘hot spot’. Hot spots form deep in the Earth’s mantle and
periodically force basaltic magma to the surface, through weaknesses in the overlying crust, where it erupts from
broad volcanoes. Two large volcanoes were created at that time; the Focal Peak Volcano near Mount Barney, and
the later Tweed Volcano. The Tweed Volcano (approximately 100km in diameter) stretched from Lismore (NSW) in
the south to Tamborine (QLD) in the north, from Mt Lindesay (QLD) in the west and fourteen kilometres out to
sea11.
Figure 1 – The inner structure of Earth and the succession of major extinct volcanos from the Australian continent moving
over stationary 'hot spot' modified from Willmott, 2010, page 9)
The shield shaped Tweed Volcano built up from many lava flows over a period of 1 million years. The majority of
the lava was highly fluid basalt which flowed long distances. Towards the end of the volcano’s activity, the magma
deep below distilled into other lava types such as rhyolite. The viscous (sticky) rhyolite at first erupted explosively
to form clouds of ash, which fell back to accumulate as beds of tuff. Then some thick lava flows surged out, but the
rhyolite flows covered a much more limited area than the basalt ones. Some rhyolite magma cooled in narrow
bodies just beneath the surface plugging subsidiary vents, such as Egg Rock and Pages Pinacles. After the rhyolite
the volcano erupted basalt flows once more 11.
Figure 2 - Tweed Shield Volcano cross section (Graham, 2004)
The central summit of the Tweed Volcano was located over the present Mount Warning and is estimated to have
reached about 2000 m above sea level. After the Tweed Volcano became extinct approximately 23 million years
ago, the high mountain attracted heavy rainfall. The igneous rock gradually weathered to form rich soils
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supporting thick rainforests and many streams flowed from the peak. Gradually the streams cut deep gorges and
as erosion progressed - the valleys widened 11.
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Figure 3 - Progressive Erosion of the Tweed Volcano (Willmott, 2010, page 14)
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Stages of Erosion:
Stage 1:
When the volcano was still active the landscape would have consisted of new, bare, rocky
lava fields, strips of colonizing shrub land on older flows, and rainforest-type vegetation in
mature areas.
Stage 2:
After the Tweed Volcano became extinct, the shape of the whole hinterland would have
been dominated by the high and broad shield landscape. The height of the volcano
attracted considerable orographic rain, the basalt lavas decomposed to form rich soils
supporting rainforest, and streams were etched on its flanks in a distinct radial pattern
from its peak. The eastern streams were more active because of higher rainfall, and they
eroded quickly westward to form the broad Tweed Valley. Streams flowing to the north
formed the Numinbah (Nerang River), Coomera and Canungra Valleys.
Stage 3:
The widening and deepening of radial streams resulted in a stepped effect on the valley
sides, with scarps or cliff lines representing the more resistant rocks derived from the
Rhyolite lavas in contrast with the less resistant and softer sub horizontal layers derived
from the Basalt lavas. The plateaus between the valleys such as: Springbrook, Lamington,
Beechmont, and Tamborine are approximately the original surface of the northern flank of
the volcano. The Tweed valley is an erosion caldera, leaving only the remnant resistant
plug of Mount Warning 11
Rainfall of the Gold Coast Hinterland
As the Tweed Volcano grew, it began to affect rainfall patterns. Rain falls when water vapour is forced
upward into the cold upper atmosphere where it condenses into droplets and falls. The water vapour is
blown west from the ocean, then pushed up by the Volcano, which causes the vapour to become rain.
This is called Orographic Rain 1; a concentration of rainfall on one side of a mountain. Orographic rain
caused the Tweed Volcano to erode on the eastern side, (as can be seen in Figure 4 below) and the inland
to be dry because moisture was stripped from the clouds.
Figure 4 - Orographic rainfall diagram (source: http://hbs.bishopmuseum.org/waipio/nativestreams.html)
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Most erosion occurred in the valleys, while the ridges remained as flat plateaus such as Mt Tamborine
and Beechmont. Today, the Eastern streams are still more active due to the higher rainfall there. The
Tweed valley is an erosion caldera, leaving only the remnant resistant plug of Mt Warning.
The southern region of the Gold Coast continues to receive more rain than the northern. The orographic
rainfall on the Springbrook plateau contributes to a rain shadow over the western part of the Gold Coast.
Average annual rainfall on the Gold Coast varies. On the coast and in the northern half of the City it is
around 1500mm. However, in the Springbrook area, the average rainfall is that of 3000mm per year 3.
Questions
1. What is the difference between the average annual rainfall at Springbrook to the average annual
rainfall at the northern half of the Gold Coast in millimetres?
2. Sketch a diagram to illustrate the phenomenon that results in Springbrook receiving a higher
annual rainfall than its hinterland. Hint: use a cross section showing the topography of the terrain
from East (Pacific Ocean) to West (Springbrook Plateau) as an outline.
Gondwana Rainforests of Australia World Heritage Area
The Gondwana Rainforests of Australia World Heritage area, originally listed in 1986 to cover rainforests in
New South Wales, was extended in 1994 to include rainforests on the Queensland side of the border.
The Gondwana Rainforests of Australia World Heritage area meets three of the four natural criteria for listing:
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represents a major stage of the earth's evolutionary history;
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is an outstanding example of ongoing ecological and biological processes; and
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contains the most important natural habitats for conserving biological diversity.
Protected areas in this property include Lamington, Springbrook, Mt Barney and Main Range National Parks.
An estimated two million people a year visit this World Heritage area.
Rainforests on both sides of the border contain more frog, snake, bird and marsupial species than anywhere
else in Australia. This site provides a home for many rare and threatened plants, animals, and ancient life
forms. The subtropical rainforest in Springbrook provide homes for ground-dwelling birds such as the rare
Albert's lyrebird and the endangered eastern bristlebird.
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The Yugumbeh and Bundjelung People O
Figure 5 – Timeline of Hinterland Settlement
Meenyahgu Yugambeh Dagun — Welcome to Yugambeh country.
The Archaeological evidence suggests that Aboriginal people have inhabited the Gold Coast region for
about 10,000 years before European settlement. By the early 19th century there were several distinct
groups living between the Tweed and Logan Rivers and bounded approximately in the west by
Beaudesert. They are believed to be: the Kombumerri, Gugingin, Bullongin, Minjingbal, Birinburra,
Wangerriburra, Mununjali and Migunberri. Collectively they were known as Yugambeh people and spoke
the Yugambeh language along with several distinct dialects in the region.
It is believed that the Aboriginal Kombumerri lived on the mountains during summer and on coastal
areas during winter, exerting only a seasonal impact on Springbrook in their search for food and
medicines. This area of dense forests, high rainfall and cool weather did not encourage permanent
habitation. Springbrook was considered to be of a spiritual importance due to the great beauty of the
gorges and waterfalls. Tools and stone axes have been discovered at Black fellows Falls.
Wollumbin is the traditional aboriginal name for Mt Warning. The area surrounding Wollumbin is of
traditional significance to the local Bundjalung people. Wollumbin means, ‘cloud-catcher’, or alternatively
‘fighting chief of the mountains’ because the mountain appears to 'be making its own clouds' due to
orographic cloud formation 7.
There is a dreamtime story of Wollumbin, said to be Warrior Chief of the mountain. The spirits of the
mountains were warriors. The wounds they received in battles can be seen as scars on the side of the
mountain and the thunder and lightning are the effects of their battles. When you look toward
Wollumbin from the lookout, you can see the face of the Warrior Chief in the mountain's outline 7.
Captain Lieutenant James Cook in May 1770 named the mountain Mount
Warning as he sailed by in the Endeavour on their route northwards along
the eastern coastline of Australia. The designation ‘Mount Warning’ was
meant to indicate the danger of the offshore reefs they encountered 7.
The park was reserved for public recreation in 1928 and dedicated as a
national park in 1966. The area is part of the Shield Volcano Group of the
World Heritage - Gondwana Rainforests of Australia inscribed in 1986 and
added to the Australian National Heritage List in 2007.
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 - Best of All Lookout
Cool Temperate Rainforest
Figure 6. Cool Temperate Rainforest diagram (modified from The Royal Botanical Gardens and Domain Trust, 2012a)
Cool temperate rainforest occurs at altitudes more than 900 meters above sea level, were the climate is
cool with high annual rainfall (1700 – 3000mm) and there are fertile soils. The forest structure is simple
with one or two strata of canopy. There is only one to three dominant tree species. Trees have simple
leaves with toothed margins, generally under 7.5cm long. Epiphytes, mosses, and lichens form dense
coverings on tree trunks and branches. The forest floor has various ferns including tree ferns.
Strangler figs, palms, buttress roots, large epiphytes (e.g. staghorns) and woody vines are rare or absent
in cool temperate rainforest.
Antarctic Beech
Antarctic Beech (Nothofagus moorei) is only found in cool temperate rainforests of New South Wales and
south East Queensland. The Antarctic Beech was very common when Australia was a part of the
Gondwana supercontinent, but as Australia moved north and became hotter and drier, the species
became less common. Fossil evidence of Antarctic Beech has been found in South America, New Zealand,
and Papua New Guinea indicating that these landmasses were once connected.
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Questions
1. Describe the features of the rock outcrop and its weathering on the side of the track after leaving the
lookout (colour, grain size, layers, vesicular (full of bubbles), glass like, and others):
2. Name the rock at this site.
3. The diagram opposite represents
the geological time scale. From the
diagram determine:
i. Age of the oldest dated rock.
ii. The era and period at the time of
the Tweed Volcano eruption.
iii. The epoch when you were born.
Figure 7.- Geological Time Scale (source: http://www.caveofthemounds.com/geotimeline.htm)
4. The small stand of Antarctic Beech trees are at 1000m which ensures a suitable temperature and
rainfall. What will happen to the species and the organisms relying on them, if the climate continues to
warm?
5. How would the discovery of the Antarctic Beech fossil on different continents be evidence of
continental drift?
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Figure 8.-a) Gondwanan fossil distribution map source:.
http://australianmuseum.net.au/image/Gondwanan-fossil-distribution-map) b) Image of
Antarctic Beech pollen, 50 Micrometers (um) = 0.05 Milimeters (mm), source:
http://www.geo.arizona.edu/palynology/nsw/shimeld/nothofagus_moorei.jpg
 Boy-ull Creek
Dry Sclerophyll Forest
Figure 9 – Dry Sclerophyll Forest diagram
Dry Sclerophyll Forest communities develop in areas where the rainfall exceeds 600mm. They also occur
in high rainfall areas where the soil is infertile or shallow and does not retain moisture. Springbrook
Plateau has high rainfall but where the soils are developed on rhyolite flows they are very infertile and
clayey. The ground cover can be grass or shrubs, depending on the length of time since the last fire.
Characteristic Features of Dry Sclerophyll Forest: Tall eucalypts, understorey of scrubs, grasses, ferns,
open canopy 30-70%, rainfall 1500mm p.a., poorer soils, dominant species-eucalypts, acacias and
casuarinas.
Tallanbana in Yumbabeh language is: out of the rushes
Boy-ull in Yugambeh language means hill top.
Questions
Look northwards from the bridge over Boy-ull Creek. Observe the cliffs of pale coloured rock that
extends along its sides. The outcrop shows flat surfaces of light coloured rock called ___________________
with contorting flow banding.
The rhyolite rock weathers and forms soils that are acid, poorly developed, often shallow and rocky and
infertile. These soils develop directly over hard unweathered rock or decomposed rock.
The forest after the crossing of the bridge is called Dry Sclerophyll Forest.
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 Ee-jung Creek
Figure 10. Classification and flow characteristics of volcanic rocks
Figure 10 – Classification and flow characteristics of volcanic rocks source:
http://volcanoes.usgs.gov/images/pglossary/VolRocks.php
Questions
The major factors which determine the rate of weathering are; climate of the area, time scale, vegetation
soil, and chemical composition of the rock.
Weathering is the destruction of rocks by two means:
Physical weathering is the breaking down of rocks into smaller blocks/particles through natural
processes due to pressure and/or temperature. The breaking down can be caused by freezing water
(when water fills cracks in rocks in cold climates it often freezes, making the cracks larger); salt wedging
(rainwater that fills cracks in warm climates as it evaporates may leave behind salt and crystals begin to
grow and create wedges), plants (as plant's root systems develop, it cracks the earth/rocks around it and
these cracks enlarge over time), temperature fluctuations (rocks expand in hot air and contract in cold
air and in time, this movement crumbles rock);
Chemical weathering occurs when a reaction between a primary mineral within a rock structure
and water with dissolved chemicals, cause the formation of a new secondary mineral.
1. List some evidence of weathering that you see on the rock here?
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 Tamarramai Falls
Warm Temperate Rainforest
Figure 11 - Warm Temperate rainforest diagram (modified from The Royal Botanical Gardens and Domain Trust, 2012c)
Warm-temperate rainforest is a cool moist habitat on fertile soil with a rainfall of over 3000mm annually.
Two tree strata form an even canopy. Its vegetation is less diverse than in Subtropical Rainforest with
usually only three to fifteen species in canopy. Leaves are mostly simple and toothed, over 7.5cm long
and on average smaller than in Subtropical Rainforests. Dominant species are coachwood and brushbox.
Stranglers, palms, plank buttresses, and woody vines are rare or absent. Tree trunks are slender and
uniform. Epiphytes (mainly lichens) are common but not obvious. Ground ferns are common.
Questions
1. Describe the features of the rock outcrop and its weathering on the side of the track after leaving the
lookout (colour, grain size, layers, vesicular (full of bubbles), glass like, and others):
2. Name the rock at this site._______________________________________
3. Describe evidence of chemical and physical weathering at this site?
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 TWIN FALLS
Questions
1. The pie graph below represents the main chemical compounds present in basalt and rhyolite rock 8.
Basalt
SiO2
TiO2
Rhyolite
Al2O3 Fe2O3
FeO
MnO MgO CaO
Na2O3
K2 0
For each rock, estimate the percentage of:
silica (SiO2)
%
P2O3
H20
%
iron oxide (Fe2O3 + FeO)
%
%
magnesium and calcium oxide (MgO + CaO)
%
%
The soils developed from the weathering of basalt rocks are red to brown, strongly structured clay soils
(50-70% clay) ranging in depth from less than 1 m to over 7 m. The red colour is formed by an oxidation
reaction between water and the iron in the basalt rock during the chemical weathering. This results in a
rich soil for growth.
2. How would you classify the type of forest type you observed growing in this
fertile basaltic soil?
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 Stratigraphy - the study of layered volcanic rocks
Questions
1. Label the diagram with the correct rock types (rhyolite, basalt and tuff).
Figure 12 –Rock outcrop diagram
2. In the figure above draw two arrows representing the main forces (pressure) acting on breaking down
the rocks due to physical weathering at this site?
3. What evidence of chemical weathering can you see at this site?
4. What inference can you make in relation to the age of the each one of rocks at this site?
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 Landslide Area
In 1890, rural inhabitants, of what is now the Gold Coast, noticed the sudden appearance of a large scar
just below the Springbrook cliffs. A large landslide had resulted in the leveling of the forest in the area in
which you now stand.
Questions
1. What factors cause landslides to happen?
2. What evidence can still be seen today?
 Subtropical Rainforest
Figure 13. Subtropical rainforest diagram(modified from The Royal Botanical Gardens and Domain Trust, 2012b)
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Warm moist habitat on fertile soils with a rainfall of over 1300mm annually; two or three tree strata
forming a multi-layered billowing canopy; ten to sixteen tree species in canopy.
Tree leaves are mostly compound, not toothed; leaves or leaflets over 7.5cm long; stranglers, palms,
plank buttresses, epiphytes and woody vines prominent; and large leaved herbs and ground ferns
common.
Characteristic features of subtropical rainforests include:
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mixed composition of many tree species with no obvious domination by any one species
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trees of large to medium size with a range of leaf forms
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palms, strangler figs, buttressed trunks, large vines and large epiphytes common and diverse
Blackfellow Falls are known as maibin jabang ( = blackfellow's ghost) by the Yugambeh
people
 Wedge Bluff Lookout
Montane Heath
Figure 14 - Montane Heath diagram
Montane Heath occurs as shrubby vegetation on rocky infertile soils, notably along cliff edges and cliff
faces. This vegetation is characterized by grass trees, banksias, bottlebrushes, hakea, mint bushes, tea
trees and other long-growing heath plants.
Questions
1. Name the rock at this site.
2. Looking at the view identify the following: Burleigh Headland, Coolangatta, Nerang River, Tallebudgera
Creek, South Stradbroke Island and Pacific Ocean.
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References
1) Bureau of Meteorology, (2012), Cloud formation and rainfall, viewed on 15 July 2012,
http://www.bom.gov.au/info/ftweather/page_9.shtml.
2) Crisp, C and Crisp, J. (2006) Springbrook Its Parks, Walks and Wildlife a visitor’s guide
3) Gold Coast City Council, (2012), Our Living City Report 2004–05, Chapter 2, viewed 10 July 2012,
http://www.goldcoast.qld.gov.au/attachment/publications/our_living_city0405_chp2.pdf
4) Graham, B (2004) The Green Coast Southern Cross University, Lismore
5) Hinze Dam stage 3 Environment Impact Statement, downloaded in 10 July, 2012 from
http://www.hinzedamstage3.com/PDF/eis/section_04_topography_geomorphology.pdf
6) Hunter, J, (2011) Under the canopy a guide to rainforest of NSW, downloaded in 10 July, 2012 from
http://www.environment.nsw.gov.au/resources/education/20100158UnderTheCanopyAll.pdf
7) McPherson, M.,(1999), Minjungbal Aboriginal Cultural Centre, viewed 12 July 2012, <
http://www.bigvolcano.com.au/stories/minjung/aborigin.htm>
8) Richards, H.C., (1916), The volcanic rocks of south-eastern Queensland. Proc. R. Soc. Qld 27, pp.105-204.
7) The Royal Botanical Gardens and Domain Trust, (2012a), Cool-temperate Rainforests , viewed 12 July 2012,
http://www.rbgsyd.nsw.gov.au/education/Resources/rainforests/Australian_Rainforests/Cool-temperate_rainforests
9) The Royal Botanical Gardens and Domain Trust, (2012b), Subtropical Rainforests , viewed 12 July 2012,
http://www.rbgsyd.nsw.gov.au/education/Resources/rainforests/Australian_Rainforests/Subtropical_rainforests
10) The Royal Botanical Gardens and Domain Trust, (2012c), Warm-temperate Rainforests , viewed 12 July 2012,
http://www.rbgsyd.nsw.gov.au/education/Resources/rainforests/Australian_Rainforests/Warm-temperate_rainforests
11) Willmott, W. (2010), Rocks and Landscapes of the Gold Coast expanded third edition, Geological Society of Australia
Incorporated, Queensland Division, Brisbane.
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TWIN FALLS CIRCUIT
N
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When you see this symbol in
your booklet:
1. Mark an X to represent
your position.
2. Take a compass bearing
to determine the direction
you are traveling.
Figure 15 – Topographical Map of Twin
Falls Circuit, Springbrook
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