14 Vet Ours

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14th Int. Symp. Vulcanospeleology, Undara: Cave Tours 1

14thInternationalSymposiumonVulcanospeleology

Undara,NorthQueensland,

Australia

12-17August2010

CAVETOURS

There will be three standard cave tours and, probably, one special (Bayliss

Cave).

The standard tours will run concurrently on the afternoons of 13, 14 and 16

August. Up to twenty people will be accommodated on each tour. People will

be assigned to tours so that everyone will see each of the caves that they bookfor. We may be joined by other Undara guests on these tours.

Tour One: Wind Tunnel Complex & Kalkani Crater

This tour commences with a descent into entrance No. U45, Misplaced Arch (apparently its

location was wrongly recorded by the original surveyors).

The arch is about 20 m wide and only about as long.

One ascends from the western end into an elongated depression which is clearly the result ofthe original tube collapsing. This vegetated depression leads to the next section of tube,

known as Mikoshi Cave U44. It was originally called Great Expectations but a Japanesemember of the Project Raleigh survey team in 1989 called it Mikoshi, meaning a good

view, and the name stuck. This is a straight tunnel 46.6 m long with arching entrances over

14 m wide and 10 m high, with a red clay floor pitted with drip craters. Prominent walllinings can be seen on the base of the southern wall.

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A rockpile is ascended at the western end of Mikoshi, opening into a closed depression. Atthe western end of this the obscure entrance to Inner Dome Cave U41 is passed and the tour

descends into the Wind Tunnel, U42.

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From the 11 m wide entrance a boulder slope descends to an earthen floor. The first sectionof tube is 37 m long, up to 20 m wide and up to 9 m high. An opening on the left links to the

Wind Tunnel proper which experiences strong thermal winds hence its name. The main

passage is 230 m long, up to 11 m wide and 8 m high. As elsewhere, in places the roof isstained bright red.

This has been a nursery cave for two species of bent-wing bat (Miniopterus sp.) and a roost

for a small population of the eastern horseshoe bat,Rhinolophus megaphyllus.

After exiting Wind Tunnel, the tour group returns to the bus and travels the short distance to

the Kalkani Crater.

A graded track leads up the side of the crater and around the rim, a total distance of 2.5 km

which takes about an hour and a half to walk. This crater is only about 20,000 years old andis not related to the Undara lava tubes. Its no Kilauea, but gives an indication of the size

and form of the volcanoes of this region. From the rim there are views over the surroundinglava plains.

View into Kalkani Crater from the rim.

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Tour Two: Arch Complex

This tour commences by descending the stairs in the elongated collapse which separates

Stephenson Cave from Arch Cave (parts of the same original tube). The roof of Arch Cave

is notable for being remarkably flat. It is 25 m wide and about 11 m high. It is the result of

collapse but the walls are pretty much as originally formed, as indicated by dribble and

drip textures. The original floor is covered by metres of sediments and collapse material

from the roof.

The wall colours indicate some of the mineral content of the surrounding basalt. The basalthere contains nearly 50% silica (which suggests that the Undara eruption was not an

explosive event) as well as about 6-8% calcium and a similar percentage of iron. Thus we

have pale deposits of calcium carbonate and reddish brown iron oxide.

Passing through the short Arch Cave (only 25 m), one enters a heavily-vegetated circular

collapsed depression. This gives access to the right and left branches of Ewamin Cave. The

shorter, right branch is not entered; it contains a semi-permanent pool which is vital to thelocal wildlife in the dry season. The left branch, which is up to 20 m wide, is traversed for

about 100 m; it is home to a colony of bent-wing bats.

The metal poles on the left-hand side are to detect any movement in the roof structure.

The name of this tube derives from the Aboriginal people who formerly inhabited this area

(the Ewamin or Ewaman). The available evidence suggests there was no pre-European

human occupation of the darker parts of the tubes. However stone artefacts and foodproducts such as fresh water mussel shells indicate there was hunting and gathering and

possible occupation in the collapses where there was a diverse range of fauna and flora.Some old bottle trees still display steps on their trunk, which were chopped by Aboriginal

people climbing the trees to harvest the seeds.

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Returning through Arch Cave, the tour traverses the elongated depression, north to

Stephenson Cave. This cave is 160 m long, up to 25 m wide and around 5 m high. Thereare some fine tree root displays in this cave.

The terminal chamber is occasionally used by bent wing and eastern horseshoe bats.

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After heavy rains Stephenson Cave can have elevated water levels in its terminal chamberfor months, as was the case in September 2009.

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The tour normally terminates at the end of the path but we may be able to proceed on to thelake which fills the width of the passage.

Barkers is the most important cave bat habitat in the McBride Province, supporting all five

species that occur in the region. Four of these breed in this cave. Nursery populations of upto 200,000 bent-wing bats have been recorded. Barkers Cave has a surveyed length of 905

metres.

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The tour will then move to Road Cave, the earliest recorded cave in the region. Road Cave

is 220 m long, up to 9.4 m high and 21.2 m wide. It is the only Undara cave equipped for

wheelchair access.

A semi-permanent spring at the entrance is used by the local wildlife, was probably animportant source of water for the Aboriginal inhabitants and was used by early travellers

through the region.

Light coloured streaks on the walls are secondary deposits leached by percolation water fromabove.

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Special Tour: Bayliss Cave

The long entrance scree runs into a dog-legged tunnel at least 1.3 km long (the longest lava

tube known in Australia). It has a maximum height of 11.5 m and is up to 25 m wide.

The cave slopes gently down to the 1 km mark before rising again after being joined by a

secondary tunnel from the East. The floor is of deep red clay with guano cover in places and

frequent drip craters; there is a rock fall at about 600 m in the middle of the northern bend. A

construction 'The Wall ' at the 900 m mark forms a duck-under. Secondary precipitate

(flowstone) has formed on the roof and walls in many places; the roof exhibits lava

stalactites to 6 cm in length; the roots of surface vegetation have exploited joints in the roof

and hang to capture moisture from the caves humid atmosphere or reach the clayey floor toform columns. A large colony of bent wing bats (Miniopterus sp.) uses the cave as a nursery

whileRhinolophus megaphyllus use it as a roost. The cave houses one of the most diversespecialised arthropod faunas known. The cave is subject to varying levels of carbon dioxide

which tends to increase with distance from the entrance.

Cave details derived from

GODWIN, M.D. 1993 Undara and associated lavafields of Mc Bride Plateau: A speleological fieldguide. Chillagoe Caving Club: Cairns

UNDARA EXPERIENCE n.d. [Notes on] Archway Complex

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