Geelong Naturalist : monthly magazine of the Geelong Field Naturalists Club

20 Pages·2002·5 MB·und

GEELONG NATURALIST
MONTHLY PUBLICATION OF THE GEELONG FIELD NATURALISTS CLUB INC
Vol. 38 No. 8
December 2002
ISSN 0726-7363
GEELONG NATURALIST
m. 4 Vol. 38 No. 8
December 2002 NAZ ED - ISSN 0726-7363
ANB
E У Wt
9» di 9
К» D N<
QD
CONTENTS
Club Notices
1
President's Corner Diana Primrose 1
Out and About Valda Dedman 2
Excursion to Mt Elephant and Lismore Birds Diana Primrose 3
Volcanoes of Western Victoria—an illustrated talk given by Bill Birch
at the 5 November 2002 General Meeting Deborah Evans 4
Competitive Bird-watching in the Long Forest and
the You Yangs Marilyn Hewish and Rob Mckenzie 7
Plant Group Dick Southcombe 8
Mammal Trapping Trevor Pescott 8
Plant Ramblings Valda Dedman 9
Library Notes Heather Cameron 9
A Red-necked Phalarope Phalaropus lobatus at Hospital Swamp, Geelong
Craig Morley and John Newman 10
Bird Group Report—Painted Snipe John Bottomley 12
Mid-week Bird Group Excursion Report Rhonda Jennings 14
Bird Group Observations John Bottomley 15
News Bites
16
COMING EVENTS
DECEM Challenge Bird Count
3 General Meeting: Members Night at Geelong Botanic Gardens
10 Plant Group Excursion
19 Mid-week Bird Group Excursion Belmont Соттоп- Leader: Don Jennings
JAN 16 Mid-week Bird Group Excursion—Limeburners Lagoon, Corio. /.
18 Saturday, 7; Day Excursion: Botanic Gardens—Leaders: Ray Baverstock, Bob Preston
21 Bird Group: 'Finding more of our elusive birds' (Team effort)
TBA Summer Wader Count
29-4/2 Campout: Howmans Gap Alpine Centre—Leader: Dick Southcombe (*)
2003
FEB 4 General Meeting: Marine Life of Edwards Point—Dorothy Mahler and Noel Schleiger (*)
11 Plant Group: Workshop Meeting
16 Excursion: Edwards Point Marine Life foreshore—Dick Southcombe, Dorothy Mahler
and Noel Schleiger (*)
18 Bird Group: ‘Birds of Lake Victoria’ Marilyn Hewish
25 Biodiversity Group: Workshop Meeting
Note: (*) indicates changes to the program
The Club Website & home page
GFNC Web page: http://home.vicnet.net.au/~gfnc/
No email address: please use email addresses of committee members on the back page
GEELONG NATURALIST Vol. 38 No. 8 December 2002
Half-day Excursion
SUMMER CAMPOUT
Saturday, 18 January 2003 ..Dick Southcombe
Geelong Botanic Garden
21st century garden Our summer campout will be held
at Howmans Gap Alpine Centre,
Falls Creek.
Leaders: Bob Preston
Ray Baverstock
The Centre is available from
dinner Wednesday 29 to breakfast PRESIDENT’S
Meet at the Geelong Botanic
(plus a cut lunch) Tuesday 4
Gardens at 9.15 am sharp. CORNER
February.
December 2002
Take the new road from the corner
Cost is $46.00 per day, i.e. dinner,
of Garden Street and Hearne
bed, breakfast, lunch. Blankets ..Diana Primrose
Parade, park in the Botanic Drive
and pillows are supplied, and there
car park.
are plenty of rooms.
We are enjoying a very different
We will examine the new 21st venue for our December meeting
As some members have already
Century Garden which contains this year, and are very happy to
indicated a preference for the 6
plants that have adapted to have been invited to do so! We
night stay, the Centre has been
Geelong’s dry temperate climate. look forward to welcoming Jayne
tentatively booked for that period.
Salmon (President of the Friends’
If time permits we will also stroll of the Geelong Botanic Gardens),
The GFNC committee requests
through the original Botanic John Arnott (Curator GBG), and
our members and members of
Garden. Rob Small (General Manager
other clubs who would like to join
Environment & Recreation with
us, to book the accommodation
COGG) to join us tonight. GFNC
they each require by forwarding a
has been invited to join with
deposit of $20.00 for each day's
FOGBG and like minded groups,
accommodation needed, to the
in initial discussions on the second
Treasurer, GFNC - Howmans,
stage of the Gardens development
Box 1047, Geelong 3200 by
FEBRUARY 2003 plan, which involves the building of
Tuesday, 10 December. Those
an ‘education/information/meeting’
General Meeting
who cannot stay for 6 nights must
centre. This is a very exciting
and Excursion clearly state which nights they will
proposal if eventually our Club can
be staying at the Centre.
have a joint permanent ‘home’ in a
Unfortunately Ken Bell is unwell -
, vibrant first class facility. So — get
and apologises for not being able All who have booked will be given a feeling for the setting and the
to speak at our general meeting further information by 20 atmosphere of these wonderful
and lead our club excursion in December. gardens tonight, and our high
February. Hopefully it won't be hopes for the future!
long before Ken is fit again and We do hope members of other
able to share his knowledge of clubs are able to accept our As we always say — ‘how the year
micro-fossils with us. invitation and we look forward to has flown!’ There are so many
enjoying Victoria's high country
‘years’ — the calendar year, the
We are fortunate that Dorothy with them. financial year, and — our Club year!
Mahler — who has a fine shell Our Club year ends in April, the
collection — and Noel Schleiger are Enquiries: time when we elect our new
Dick Southcombe 5243 3916
available during February. They committee! Just as a nice present
will speak to us about the marine to our Club next April, it would be
life of Edwards Point — with so good if YOU could start
emphasis on the Mollusca — on considering who would be a good
Tuesday 4th February and lead a m candidate (even yourself!), and
beach excursion there on Sunday %&6& 66666666146 3 start working on it now! It would be
16th. We thank them for helping at 3 so good for the Club to have a full
We welcome
short notice and invite them to join б Committee! Please!
Li new member
our March excursion when the
Ф Mr Doug McDougall Ж
local ‘Friends’ will lead us to other
Edwards Point/Swan Bay features. to the Club and wish
б
him a long and happy
б
association.
Я
ba NI BEEEBEBBEEBEE
WAS (More notices on pages 8 & 14)
GEELONG NATURALIST Vol. 38 No.8 December 2002
has four enormous black eyes. All
to help them not get eaten.
Out and About
Snakes have a transparent
covering over their eyes and
...Valda Dedman
cannot focus very well but can pick
up movement very quickly. They
have no external ears; they hear
through their bellies—vibrations
being transmitted upwards to the
inner ear. They taste the air with
Birds' eyes have a third eyelid, a
their forked tongue.
Why do so many people find bat
nictitating (winking or blinking)
faces gruesome? Have they ever membrane that helps to keep them
A flying fox has a long pointed
seen one up Close, in real life? The free of dust etc. Normally folded up
tongue that is covered with
tiny Micropterans tend to have
in the corner near the beak, it
backward-facing scales, which
rather weird faces, with warty
comes across as needed, for
help it gather pollen, drink and
projections or nose spikes, and instance when the bird is pecking
groom. Lorikeets, honeyeaters and
large elaborate ears ribbed with
grain. Humans have but a remnant
silvereyes have brush-tipped
cartilage. These all help the bat's
third eyelid. What a pity!
tongues, good for lapping up
sonar echo-locating system
nectar. Honeyeaters' tongues are
operate more efficiently, to home in
Spiders generally have as many
very long and can be rolled
on prey and magnify sounds.
eyes (ocelli) as they have legs, and
inwards to form a tube to scoop up
the pattern in which they are
the sweet fluid.
Bird parents find the wide-open arranged is a clue to identification.
mouths of naked babies in the nest
Two rows of four or three rows,
Which bee is it? You could ask it to
perfectly irresistible, even if one with four little eyes, then two large
poke out its tongue. The family
baby is a cuckoo imposter. That ones and two middle-sized ones,
Colletidae, which make up about
one is likely to have the widest
or whatever. A huntsman can see
half our Australia's native species
gape and so will get the largest
ahead, to the rear, sideways and
have short blunt tongues, while
share of food. Nestlings' mouths
above, all at the same time.
Halictidae have short pointy ones,
may have brightly coloured or Jumping spiders have two large
and Megachilidae and Apidae have
patterned linings. The Gouldian eyes at the front and binocular
long tongues. Colletid bees use
Finch's gape has beads that glow vision so that they can pounce
their tongues to weave
in the dark, for the nest is deep accurately on their next meal.
celllophane-like nests from a clear
inside a hollow tree.
liquid that instantly hardens. One
Some caterpillars deliberately
sixth of Australia's native bees are
You are not meant to see a
confuse. Hawk moths have two
Hylaeine or Masked Bees, so
frogmouth's head at all, or its body eyespots near the head. The Noela
called because they have white or
either, as it mimics a bit of branch. Moth caterpillar has a fleshy spike
golden spots on their faces which
During the daytime it keeps its big at its posterior end, with an
make them look as if they are off to
mouth shut and its eyes closed. eyespot concealed in a crease
rob a bank (or a florist's shop).
Bristles around its mouth break up underneath it. The Gum Leaf
its outline.
Skeletoniser wears a hat made out
An orchid tongue (labellum) is
of its old head skins. The stout
often decorated with calli — little
If you cant see a frog's eyes, it green Black Noctuid caterpillar has
lumps that are arranged as a path
may be eating. Frogs' eyes are
two spots like little white eyes at its
to direct nectar-seeking insects
large. 'All the better to eat you with, rear end. The Wanderer caterpillar
past their pollen. Greenhoods snap
my dear!' Most frogs do not chew has a pair of fleshy black filaments
their mouths shut and trap the
their food. Prey is caught on their at either end. The Ringed Xenica
insect until the mission is
flypaper tongue. If it is too big they
has two horns on its head, like little accomplished.
will shove it right in with their cat's ears.
hands (no manners). Then their
| hope by now you will be so full of
pop-eyes are pulled right down And the adults also practise
questions that you will spend the
inside the mouth cavity and the
deception. They have eyes painted
next two months asking ‘Why is it
whole food item slides against on their wings. The Old Lady Moth
so?’ And taking a second look at
them and into the throat.
in her drab grey dress has eyes of
the faces around you. Happy
watery blue. The Emperor Gum
holidays!
Depending on the species, the has magnificent orange eyes. The
pupil in a frog's eye can close to a
Swordgrass Brown has blue eyes
vertical or a horizontal slit, a on its forewings and large orange
rhombus or a diamond. Your own eyes with large dark pupils on its
pupil stays round as it contracts. hind wings. The Meadow Argus
Birds can control the size of each has a whole row of blue eyes
pupil independently. ringed with orange, The tiger-
coloured Eastern Ringed Xenica
GEELONG NATURALIST Vol. 38 No. 8 December 2002
credit to Derrinallum and Lismore
communities working together to
Excursion Report raise the funds to keep their mount
in local (and now public) hands.
Mt Elephant and Lismore Birds
17 November, 2002 The Committee holds regular
working bees to rehabilitate the
area — rabbits and weed species
..Diana Primrose being the major concerns. Some
planting of indigenous Poa
species has been done. It is not
planned to plant any tree species
on the mount as the well known
back again!), but some of us did
‘elephant’ landmark is to be
А warm day (forecast 33°C), but
walk up to the trig point on the
maintained. It is hoped that Mt
it was overcast to start so quite summit and circumnavigate the
Elephant will attract visitors to the
pleasant travelling. Fifteen of us rm. -
area and provide business for the
were not deterred by the prospect
local towns. A successful ‘Music
of a hot day, and made our way to We saw some very small Blue
on the Mount’ evening has been
Derrinallum taking the ‘scenic Bells (Wahlenbergia sp.) and
held the last two years.
route’ via Cochranes Road Wood Sorrel (Oxalis sp.), and of
through the Barrabools and course thistles various! The distant
Following lunch on the mount, we
Gnarwarre to the Hamilton views are magnificent — across to
proceeded to meet up with Bob
Highway. A small wetland area the Grampians, Mt Bullengarook,
Hughes at his place, for an
along the Gnarwarre road the Pyrenees, and many other
afternoon of ‘birding’. Bob took us
produced some interesting birds. landmarks. Heat haze did reduce
into Titanga Station, which was
distant visibility somewhat, but
historically very interesting in itself,
In Derrinallum township we met up Derrinallum township апа
being one of the original station
with Peter and Janine Davis, surrounding farmland was like a
properties settled in the 1800s.
members of the Mt Elephant picturesque miniature made from
We drove in to two of the big dams
Community Management a child's nursery blocks. Raptors
to check out the bird life and were
Committee. The information various flew overhead (my thanks
not disappointed in spite of the hot
shelter on the town’s median strip to Craig Morley's expertise in
day — brolgas, native hens, duck
is a fagade designed on the style compiling the bird list).
species various, stilts, etc. We
of the early settler's houses — local
also noticed the Damsel flies and
stone with brick surrounds to the As our geology books tell us — Mt
Dragon flies skimming across the
door and windows. There are Elephant rises some 240 metres
dam, and heard the Growling
historical photos of the area and above the surrounding Western
. Grass Frog [now renamed Warty
an introduction to Mt Elephant — a District plains, with its well
Bell Frog].
good starting point for a trip up the preserved crater dropping 90
mount. Peter led us up the mount metres into the mountain. lt is
. We paused to admire the historic
‘the old way’ through the quarries, registered on the National Trust's
bluestone shearing shed and
currently a restricted area. We 'Register of the National Estate' as
completed the day having
noted some whitewash on the 'one of the highest, and one of the
afternoon tea along the front
quarry cliff face — later peregrines major scoria cones, in the largest
driveway — a marvellous parkland
were sighted. homogenous volcanic plains on
of many species of trees planted a
earth’. There are two main
century or more ago.
Peter walked us through to a breaches where small flows of
second quarry area which is to be basalt occurred. The fragments
a public car park when Mt thrown out by the volcanic activity
[64 species of bird were seen and
Elephant is officially opened to range in size from fine ash to
the record has been forwarded to
public access in early December. coarse bombs and blocks. It is one
Marilyn Hewish for inclusion in the
A new road has been put through, of the world's youngest volcanoes,
Geelong Bird Report.]
in part following the path of the old with its distinctive shape making it
quarry railway. The quarry face a major navigational point for early
here shows clearly the different explorers and travellers setting out
strata of volcanic ash, tuff, and across the Western District plains.
basalt rock. After ‘geologising’ Mt Elephant had been privately
here, looking for insects under owned since white settlement until
rocks, and raptors above, it was a the year 2000, when it was
steady climb to the crater up a well purchased by the local community
graded track. Some were ferried in partnership with Trust for
by Peter in his 4x4. We did not Nature. It is now managed by the
climb the 90 metres down into the Mt Elephant Community
crater itself (and the 90 metres Management Committee — a great
GEELONG NATURALIST Vol. 38 No.8 December 2002
but most of it was derived by the
melting of the mantle and lower
Volcanoes of Western Victoria —
crust. The lava rises to the surface
report of the talk given along fractures, usually when the
crust is a bit under tension, and the
by Bill Birch
lava's composition changes as it
at the General Meeting, 5 November, 2002 rises through tens of kilometres,
resulting in slightly different
compositions when it gets to the
..Deborah Evans surface.
The effusive or quiet volcanoes
There are two types of volcanoes—
quiet or explosive—and we'll look at
of the State. There are about 400
This is a topic in which most the quiet ones first as they're the
known eruption points, with a heavy
Victorian geologists are interested. concentration north west of ones that built up most of the lava
Contrary to popular understanding, Melbourne in the central highlands plains. They're generally older, and
there have been volcanoes in area, but they stretch all the way are pretty inconspicuous, generally
Victoria quite recently. For the last across to Mt Gambier in South forming low hills surrounded by a
70 million years, all the way from Australia, where the Blue Lake is one broad shield. An example is Mt
Tasmania to Northern Queensland, of the younger features on the plains. Pierrepoint, near Hamilton, which is
volcanoes have been sputtering probably about 4 million years old. It
away at different times, and have There's no doubt that Aboriginal would have had a crater on it
built up one of the largest volcanic people would have experienced originally, but over time that has
provinces in the world, not some of these eruptions, although eroded off.
necessarily in terms of volume, but there are no really definite legends
certainly in terms of area. And there associated with any of the particular Another example, closer to
is no reason to say the field is volcanic peaks, just vague Melbourne, on the way to Ballarat, is
necessarily extinct. references to fire coming out of Mt Cotterell. It has a similar shape,
mountains. Europeans began to with a slightly flat top, but when you
Most of the world's big volcanoes recognise features on the plains as get away from this volcano and get a
occur around the tectonic plate early as the 1830s, when Major good view of it, it’s very big. It has a
margins where the plates are rubbing Thomas Mitchell climbed Mt Napier, lot of lava flows spreading out from it
up against each other or sliding south of Hamilton and commented in different directions, and it's one of
under each other generating melting on the remarkable youthfulness of the longest erupting volcanoes of this
of the various crustal plates and the crater. The story goes (probably type in Victoria. Unfortunately we
resulting in chains of volcanoes. a bit of an exaggeration) that he don't know exactly how old it is as no
Eastern Australia is a long way away plunged his hand into some of the one has got round to dating it.
from any of these plate boundaries, crevices around the crater rim to Probably one of the best examples,
so the Victorian province is called convince himself that it hadn't but which can only be seen well from
intraplate volcanism. The activity is erupted yesterday. the air, is Mt Napier, south of
in some way associated with the Hamilton. It has a scoria cone on the
movement of the Australian plate Then in the 1850s when geological top, but it's built on top of a big,
northwards away from the Antarctic mapping started in earnest, volcanic broad lava shield volcano. There
plate. The Australian plate must be hills north of Melbourne were were two episodes in the history of
moving over hot spots or plumes in identified and marked quite this particular volcano—an early
the mantle that are bringing hot prominently on early maps. Hills in: phase where it built a shield with lava
magma up below the crust and every the Sunbury area, for example Mt going out in all directions, and then a
now and then the magma breaks Aitken, which have flat tops like a final phase which was a more
through and volcanoes erupt. The lava ridge, were recognised by the explosive one that built up the scoria
whole story is not well understood— early geologists as volcanoes, but cone.
various people have put forward could not be dated at that time. It is
models to explain the age distribution really only since the late twentieth Eruptions similar to those seen in
of the volcanoes along the eastern century that we've had access to Hawaii today would have taken place
coast, but one single model doesn't modern dating methods. in the Western District to build up the
work. lava plain, with very fluid lava flowing
away in all directions at a very fast
We don't know exactly how old all
Most of Victoria's volcanoes are in the Victorian volcanoes are as only rate either from isolated vents or
the western part of the State in the some of them have been dated, but from fissures with a line of eruption
flat western lava plains of the they're of the order of 2 or 3 million points that enabled the lava to
Western District, referred to as the years, and, although there are still spread out a bit more effectively.
volcanic province. The average doubts associated with the age The lava from Mt Napier flowed from
thickness of the lava is about 80 estimates for the youngest eruptions, the volcano around 10 000 years ago
metres, so a considerable volume of it is generally accepted that the and travelled about 50 or 60 km
lava has been erupted. The volcanic youngest ones only took place down one of the stream valleys, the
province trickles off to the north of between a few thousand or a few Harman valley. It's quite fresh—
Ballarat, mostly along valleys. It tens of thousands of years ago. looking as though it only flowed a few
extends from as far as Melbourne all hundred years ago—and there are
the way across into South Australia The lava flows themselves are prominent features on it such as
(see Figure 1), though there are mainly basalts, or bluestone. The ridges and tumuli, indicating that the
isolated lava flows in the eastern part origin of the basalt is complicated, lava would have flowed quite quickly.
GEELONG NATURALIST Vol. 38 No. 8 December 2002 5
—————————————————————————————————————————————————————————————————————————————————————?
Quite often, rather than exploiting a erupts in a fire fountain, with of ash and scoria. Scoria is just
stream valley, the lava just spread out incandescent hot fragments of lava cinders—pieces of frothed up lava,
around the volcano as we can see in being blasted out and falling back to very light, which get blown into the
the stony rises around Mt Rouse, form a cone. They would probably air, then fall back down again, usually
which is one of the prominent have resulted from a single episode, solidifying in the process. The
volcanoes in the Western District. taking from several months to several : material that builds up tends to be
Stony rises occur when the crust of years to build up one cone before fairly loose as the pieces don't stick to
the lava congeals and forms a hard going dead. The cones can reach each other very much.
skin while the molten lava underneath several hundred metres high, and
drains away unevenly, so that the usual have a good crater. An Scoria quarries, such as those at Mt
surface subsides irregularly leaving a example is Mt Elephant at Rouse or in the complex of scoria
hummocky feature. Derrinallum which is the biggest cones known as Red Rock, where
scoria cone in Victoria—240 m high there are about 40 eruption points;
Sometimes in a lava flow down a and 1.3 km across at its base. It has make quite a mess of the volcanoes.
valley, the withdrawal of the lava in recently been bought from private Attempts are being made to stop any
the channel forms a tube, and over hands and is now being looked after more unnecessary quarrying to
time a lava cave develops. The lava by the Trust for Nature. conserve the scoria cones, but
caves at Byaduk, again on the flow
geologists are always in two minds
south of Hamilton, are some of the There are other scoria cones closer when they're asked to support such
best that you can see anywhere, with to Melbourne, such as Mt Fraser and conservation measures, and to stop
unusual features in the lava Bald Hill in the cluster of scoria cones quarrying in a certain district,
preserved on the walls and little north of Melbourne. Mt Fraser, which because the quarries often show
micro-environments formed in the has a big quarry operating on it, can structures which can provide
caves. Other unusual features which be seen from the Hume Highway. Mt evidence of how the volcanoes
you can see on the surface of this Fraser and Bald Hill would have erupted. In the scoria quarry at Mt
same lava flow are large blisters, or erupted mainly scoria, but some of Leura near Camperdown for
tumuli as they are
example, there are
called, which are
lumps of rock
irregular humps of & Volcanoes with máanlyWava
brought up from the
frothy lava, although A. Vüléanoes with storia
mantle or lower
people still debate Q' Maat volcanoes. 3e us crust, known as
their origin. u. a |mantle xenoliths.
c 2 ТА Teri E These provide
If a thick lava flow in a ! УЯ iг important
stream valley stops
P “ 4 $9 4 information for
and cools in the one к. A ábа, $55 Meibourne geologists about the
place, lava columns P crust beneath
develop. A well-
Victoria and a lot
known example is the
about the volcanic
basalt columns of the
e Colac 7 process itself—how
Organ Pipes, but XV a
the magma formed.
another very good one “Warrnambool N i
There are other
is in the Barfold
quarries in the west
Gorge, north of
Figure 1. Volcanoes of western Victoria (from B Joyce) which also yield
Kyneton, and there
good suites of these
are further good
mantle xenoliths.
examples in western Victoria of this the other volcanoes sent lava flows a
phenomenon. million or two million years ago down Further away from the vent the
the drainage that ran into the Yarra volcanic products are layers of ash,
Pillows textures, which form when River, reaching as far as the current often with bedding which shows the
lava flows slowly into water, are quite CBD in Melbourne. Another scoria different phases of the eruptions.
rare in Victoria but one example can cone with a good crater is Mt Franklin There may also be large blocks blown
be seen at Exford just near Bacchus near Daylesford. This is a breached out of the volcano which get
Marsh. Some spectacular crater formed when a bit of lava flows embedded in the fine ash layers
underwater footage has been out in the final phase of the eruption underneath and then gradually get
obtained of pillows forming in Hawaii and breaks through the rim of the covered up. In addition to ash and
and the example at Exford is clearly crater to form a short lava flow. Yet scoria, some of these explosive
the same sort of feature, although a another example is Birch Hill which is volcanoes produced 'spatter', material
bit weathered. It was probably a lava probably mostly scoria, but also which got blasted up but didn't go
flow into a shallow lake in the district. probably has some lava associated very far, falling back to build up a
with it. It is probably about 3 or 4 rampart such as the one at the edge
Scoria cones—the. explosive million years old and is one of the of the crater at Mt Napier.
eruptions ones from north of Ballarat (see
The younger volcanoes are Figure 1) where there is quite a Maars
responsible for the more prominent complex of interesting volcanoes of The other type of explosive eruption
features on the lava plain and this age and type. The Birch Hill which is very common on the lava
certainly the more exciting ones. complex is of national significance for plain, particularly in the region west of
Most of them would have erupted in the geological features around it. Colac, as you can see on Figure 1, is
what's known as a Strombolian-type
the maars or maar volcanoes. These
eruption, named after the Stromboli These explosive volcanic eruptions are also known as tuff rings, tuff
volcano in the Mediterranean, which discharge lots of material in the form being the volcanic ash that forms the
ЄС
6 GEELONG NATURALIST Vol.38 No. 8 December 2002
ring around them. You don't see Tower Hill is that after the main maar Getting a bit closer to home is Mt
much from the ground with this type eruption, the energy system changed Holden, which is one of the flat-
of volcano. They form subdued and a series of scoria cones erupted topped volcanoes in the Gisborne-
features, and an aerial view of them in the centre. At Tower Hill there was Sunbury area. There was a theory
is needed to appreciate their beauty also a small lava flow, but generally put forward that those flat tops were
and see their symmetry. there is not much lava associated the remains of a lava lake left in the
with these particular maar eruptions. crater after the volcano stopped
Maars form when magma rising in the erupting, and that this cooled and
crust encounters water-rich bedrock. The ash in the tuff ring around Tower sagged a little and was left as a flat
In this part of Victoria the bedrock is Hill is exposed in quarries around the cap after the surrounding softer
young sedimentary rocks, generally edge and you can see there the scoria around the crater walls eroded
sands and limestones, which are complexity of the layering. It was a away. However, evidence from a
Tertiary in. age, and full of water. virtually continuous eruption, mostly road cutting which goes through one
When the rising lava hits the fine material which spread out all of the volcanoes in that area, called
groundwater, there is a huge around the surrounding country and Fitzgerald Hill, shows that the layers
phreatomagmatic explosion, as it's is which is responsible for a lot of the are not in fact horizontal but are the
called, with the hot water turning to important agricultural benefits of the outcrop of a vertical mass of lava, or
steam and blasting the material area. Ewen's Hill, which is another dyke as it's called.
through the remaining crust above it maar complex south of Camperdown,
to form a circular crater. These also provides an opportunity to see Although they don't strictly form part
craters are quite shallow and the ash layering as well as examples of the western lava plains, there are a
surrounded by a low ring of ash. of steam channels going through the number of prominent eruption points
Generally the base of the crater is ash layers, indicating fumarolic in the Macedon area; Hanging Rock
below groundwater level, so it forms activity, with hot gases coming out as being the most interesting, and
a lake, although not all of them do well. While the initial eruption would famous. These are a different sort of
have lakes in them. Quarries in the have been very violent, it would have lava, a sticky lava known as trachyte,
surrounding tuff rings, such as the bubbled away for quite a while. which would have forced its way up in
one at Lake Keilambete, west of the vent, and largely cooled there,
Colac, give geologists very important Composite eruptions although it would have sent a couple
information about the nature of these Many of the volcanoes in the Western of lava flows out a short distance.
maar eruptions. District are what are called These eruptions are a bit older, about
composite, as illustrated by Tower 6 or 7 million years old, and formed in
Two of the most spectacular of these Hill where the maar eruption formed a slightly different way, but they're still
maars, and two of the biggest, are at the main crater with some scoria part of the overall volcanic picture in
Lake Gnotuk and Lake Bullenmerri at cones developing in it as the later or this area.
Camperdown. Lake Bullenmerri is younger phase. The same thing
slightly cloverleaf shaped, and so it happened with a lot of the volcanoes, This variety of different types of
was probably a coalescence of at although it's often not quite as volcanoes indicates why we need to
least three maar eruptions pretty obvious as at Tower Hill. Mt Leura, look at each individual volcano's
close to each other, but at slightly for example, is actually a scoria cone history separately. Evidence from
different focus. Lake Bullenmerri is built on an earlier maar. There's no quarries and aerial photography is
an example of the subdued features lake in it, but the scoria cones have needed to work out their history. The
of these maars; you don't see it from come up in the middle. Mt Noorat, biggest problem is how to work out
the road, but it's quite awe inspiring one of the most spectacular scoria how old they are. The only way the
when you come over the crest and cones, is the same sort of thing; it young volcanoes have been able to
see it ahead of you. has a prominent set of scoria cones, be dated is if a lava flow from one of
but the tuff ring, which would have the eruption points has dammed a
Lake Bullenmerri occurs next to Lake been a maar, is nearly completely stream and buried some charcoal
Gnotuk but the water levels are at buried. which can be dated by carbon dating.
different heights, and historically one Its very difficult with even the most
did drain into the other. Lake Gnotuk Mt Kooroocheang north of Ballarat, modern methods to date a piece of
is actually quite a salty lake—the which is one of the biggest and most volcanic rock, as you need to have
groundwater has become saline over spectacular of the volcanoes in certain minerals in it. However, there
the probably twenty or thirty thousand Victoria, is another composite are new methods developing, using
years since it was formed. Lake volcano. It doesn't have a crater on different sorts of isotopes, which will
Bullenmerri is not as salty as Lake the top but it has certain features probably in the long run enable us to
Gnotuk—there are fish in it and you such as scoria and lava flows date a lot of these more accurately.
can swim in it. These lakes are all associated with it which clearly At the moment there's still a lot of
shrinking a bit, not just because of identify it as a composite volcano. guess work.
the drought over the past few years, Some of the lava flows from Mt
but because climate change over the Kooroocheang and from some of the Significance of the volcanic
last 100 or so years has lowered other volcanoes in the region buried features
them. or drowned a lot of the streams at the There are many reasons to value the
time. The gravels in these streams volcanic features of western Victoria,
The most spectacular of the maar contained a lot of gold and so this stemming from their scientific, cultural
eruptions was Tower Hill near area became quite a rich goldfield, and economic significance. Firstly
Warrnambool. It's a couple of with the miners digging down to the from the scientific perspective, we've
kilometres across and has quite a cliff buried riverbeds under the lava flows, seen that the area shows very well
horizon around the northern edge, and then following them to get the preserved features of а diverse
although it tends to be subdued gold bearing gravel out. variety of types of volcano, typical of
towards the south. A feature of what we call the intraplate volcanic
GEELONG NATURALIST Vol. 38 No. 8 December 2002
province. The field also provides
evidence for the causes and timing of Competitive Bird-watching in the
volcanism in eastern Australia,
especially in relation to the way the Long Forest and the You Yangs
Australian plate is moving over the
mantle, and the rich assemblage of the
rocks that have been brought up from ...Marilyn Hewish and Rob Mackenzie
the lower crust and the mantle reveal
the nature of the metamorphic and MH,97 Grey St., Bacchus Marsh, 3340
magmatic processes in the deep crust RM,94 Christies Road, Leopold 3224
and mantle.
In the last year we have been brag about my beaut sighting, and
Other scientific studies involve looking
exchanging e-mails on our latest bird you pulled the rug right out from
at the way lava flows are weathering
sightings in the Long Forest (MH) under me! There is a veritable plague
and how quickly soils form on them,
and You Yangs (RM). The similarities of them!
with scope for working out some ways
in the bird populations in the two The flycatcher was seen flying north
of finding out how old the flows are
areas are readily apparent. Both are at Hovells Creek, fairly high, between
from the rate they weather; and
prime local examples of dry Red Gums on the west side of the
studying the records of palaeoclimates
woodland, and both hold populations creek, and | thought it could be a
preserved, for example in the pollen
of locally uncommon woodland birds Leaden - smallish with its pure white
grains, in the sediments in the’ bottom
and attract unusual visitors from the underbody and short dark hood. |
of the stable maar lakes.
northern parts of the state. Trevor briefly saw it when it landed,
Pescott (Natural Victoria, 1978, quivering its tail, but it moved on
The volcanoes are also significant for
Rigby, Melbourne) has suggested before | could identify it. |c hased on,
cultural, educational and economic
that there is a connection between verging on panic (!) when it flew
reasons. Aboriginal people, as
the two areas, with Long Forest across the creek to my side into
mentioned earlier, would have
acting as a flyway for dry-country lower trees, and began calling. My
witnessed some of the youngest
birds which reach the You Yangs description of the call at the time —
eruptions and flows, and there are from the inland. The two areas are ‘wee-cher, wee-cher, wee-cher.. | still
some sites that do still have cultural
also similar in their tendency to couldn't positively identify it. | wasn't
and spiritual significance for them.
induce obsessive bird-watching sure of the call, and as | was looking
Economically, agricultural production
behaviour in susceptible into the sun, it still looked dark like a
has benefited from the rich volcanic
personalties. Here are some samples Satin. Now that it had called, | copied
soils formed from the weathering of the
of our e-mail correspondence, with it, and soon had the bird as close as
basalts and also from the ash from the
extracts from our notes added for 5 metres and nearly at ground level —
maar eruptions. The hard-rock from
clarity. unreal! No mistaking it from then on —
the lava flows has provided bluestone
| Kept it around for about 15 minutes.
as a building material, and the scoria
Leaden Flycatcher Long Forest: On | watched it feed in low trees and
and tuff deposits on some of the maars
14/11/02, | heard a flycatcher calling. shrubs on the east bank of the creek,
and other volcanoes are a significant | couldn't quite work out from the call where it caught and ate a moth.
resource in the area.
whether it was a Restless or Satin, Beautiful dull, dark-grey colouring,
So | squeaked it in. A male flycatcher ‘ slightly darker about the head, slight
Finally, the region has significant
bored in straight away, and started crest, sideways wagging or quivering
potential for tourism. The Volcanoes
flitting around me calling, raising its of tail, occasional harsh churring call.
Discovery Trail is a new development
crest, shivering its tail and generally : A rare sight for me in the Geelong
in the Western district and the people
getting very agitated from 5 metres area. My only other possible record
in Camperdown and some of the other away. When it settled down I got the was on 2/1/59 at Wurdiboluc, but |
towns in the area are trying to attract binoculars on it, and had a sudden have seen them often in northern
some of the tourists who visit the Great jolt. Since when did male Satin Australia. і
Ocean Road by encouraging them go
Flycatchers have grey plumage with
inland along the Volcano Trail on their
a silky green sheen, a blackish area Peaceful Dove
return journey. That's yet to be around the face, and a short bib. It You Yangs: There were 2 feeding on
developed, and it will require some
was a male Leaden Flycatcher, a the ground at the camping area at
hard work. Some of the people in the
new species for the Long Forest. No the end of Beehive Track on 25/5/02.
Western District, for example, have wonder the call seemed strange! | The birds were identified by their
lived with the volcanic landscape for so
described the calls in my notebook small size (cf. Spotted Turtle-dove)
long they're a bit blasé about it. We as а rasping call, possibly harsher and narrow barring around the neck.
need to tell people the stories than the corresponding call of the They were silent. Last seen at the
associated with volcanism and
Satin, and a variety of clear whistling You Yangs on 24/6/89, when the
encourage more people to appreciate
calls, including a rising ‘chewee birds called frequently with their
its significance and we have to have chewee' and a falling ‘weeoo’. typical 'doodle-oo, doodle-oo' call.
some high standards of conservation My only other record of Leaden Long Forest: Walking up a spur from
and preservation as well. That is
Flycatchers in the Geelong region Djerriwarrh Creek on 14/11/02, |
where looking at each volcanic centre
was of a pair at lronbark Basin on heard from the creek bed a very
and trying to develop a management
3/12/89, but I've seen several in familiar call — ‘doodle-loo doodle-loo'.
plan for it is so important.
Queensland. Plain as anything, a Peaceful Dove -
You Yangs: What a surprise | got a new species for the Long Forest
The vote of thanks was given by Diana when you said you had seen a male list.
Primrose. Leaden Flycatcher – | was at the You | finished the day by going down to
Yangs yesterday (15/11/02), and also the creek in a different place at the
aw saw one! | was about to e-mail you to bottom of Bermagui Track. | flushed
8 GEELONG NATURALIST Vol. 38 No.8 December 2002
a Grey Shrike-thrush out of the Flat a brown bird with a large
shrubbery in the creek, and while | reddish forehead/cap patch апа
was waiting to see if it gave any hint similar-coloured blotch on breast.
Plant Group
of nesting, | heard every now and From memory, there was no
then a soft growling noise from indication of black on-the back, but ..Dick Southcombe
above and behind me. Call me slow, the presence of red on the breast
but it took me about 15 minutes to suggested a young male. The bird Our final meeting for 2002 will be
twig that this was the call of a could be squeaked in to quite close.
an evening excursion to various
pigeon, in fact another Peaceful
reserves in the Torquay area on
Dove. The very co-operative bird On 12/7/02, | saw 2 birds. The first
Tuesday 10 December.
then confirmed my identification by bird was on the western boundary of
giving the 'doodle-loo' call. | was the reserve, west of Barros dams —
Assemble in Waurn Ponds
happy enough with that, but then it an immature bird with no reddish
shopping centre carpark — near
flew in and perched in the open and markings, feeding in and under
Safeway Petrol Station — to arrange
let me get a look. The bird was quite Black Wattles and from the fence
far away, about 30 metres off and bordering open farmland. An adult transport for a 3.30 pm departure.
20 metres up, moving between the male Scarlet Robin arrived to briefly
branches of some huge Manna chase it, but didn’t appear overly At Jan Juc, turn off the Great
Gums. However, | could see that it concerned when the Red-cap Ocean Road into Bell’s Boulevard
was tiny, with a blue-grey head and returned to sit in the same tree and and travel to car park near WAVE
a pinkish grey breast separated by a within 1 metre of the Scarlet. Two SCULPTURE at entrance to Bells
broad darker grey band (the upper photos taken, but only with 127 mm Beach where we will meet for our
breast is finely barred in a broad lens. The second bird was seen at first walk — on new pathways —
band, but it was too distant to see Eastern Paddock. It appeared through the coastal reserve at 4.00
the barring), and with grey wings identical to the first bird, but this time pm.
with fine dark bars. | think there may with a reddish forehead. It was first
have been two birds there, because sighted in the open, but as | followed Time and weather will influence
after | had looked at one | could it for a better view, it managed to which other reserves we will visit
hear another in a different place (but escape into bordering thick scrub.
and where we have BYO tea.
the bird | saw may have moved On 20/9/02, a beautifully coloured
35
while | wasn't looking). Is there an male was seen along the track
invasion? extending from the bend in Sandy
Creek Road. It was calling most of
Red-capped Robin the time, and responded to my
Long Forest: (Red-capped Robins squeaking by coming in quite close.
have been resident in the Long At one stage, it came face to face
Forest since 1997, and have nested with a male Scarlet, the Red-cap
in each year since 2000; see drooping its wings.
Geelong Bird Report 2000). | found `
Mammal Trapping
a Red-capped Robin nest with two Woodswallows
young on Djerriwarrh Track by the Long Forest: White-browed and
..Irevor
entrance gate (25/10/02), and the Masked Woodswallows are
chicks were being fed by two brown everywhere over Long Forest this Pescott
birds. There seems to be another year. I've seen them overhead on
pair at the junction of Bermagui and almost every visit since 2/10/02.
Sheoaks area 12-15 December
Djerriwarrh Tracks, and another pair This is the first time they've stayed
under the power line near the for an extended period after the’
Meet at the Parkinsons' property, 2
northern boundary of the reserve, initial arrival on migration, and the
Stirling Road (corner Sheoak Road).
but | can't get onto any nests in first time I've seen them in woodland
those areas. There are still Red- in Long Forest. I've found a place Times
capped Robins on Gravelly Track, where White-browed and Masked 4.00 pm Thursday, 12 December to
and also several pairs in adjacent Woodswallows are pairing off, close set the traps
territories (Oldhouse Track, Happy to a Dusky Woodswallow nesting 8.00 am Friday to check traps
Valley Track). The children from the colony. That will be worth 5.00 pm Friday to check traps
last few years’ breeding at investigating later. You Yangs: On (Saturday as for Friday)
Djerriwarrh and Gravelly Tracks are 24/10/02, there were heaps of 8.00 am Sunday collect traps.
probably now setting up their own White-browed Woodswallows and a
territories. singe Masked on a fence. On Further information,
You Yangs: On 1/5/02, a pair was 2/11/02, about 10 White-browed phone Trevor 5243 4368
seen west of The Stockyards. | first Woodswallows east of the You or email [email protected]
spotted the female with her bright Yangs, and a pair at Eastern Flat
forehead, and when І squeaked, the looking a bit suspicious — | found a
Also...
male flew across my head to land in woodswallow-like nest, empty, in a
an exposed position for a great nearby tree. I'll have to watch this. OREN Calendars 2003
view. | settled down on a convenient ak available tonight, cost $10.00
rock to watch them while | had
lunch, and next thing they had
disappeared! On 25/5/02, an
immature male was seen at Eastern