At the General Meeting 2nd March 2011 Mike Cleeland spoke about granite and the Cape Woolamai Granite Quarry.
Mike started by showing a piece of Cape Woolamai (CW) granite. Every granite is different. They’re like fingerprints. CW granite is different to Wilson’s Promontory granite and Mount Martha and Tynong granite. Every granite has its own personality and chemical make-up, as each is like a solidified soup with different ingredients.
CW granite is distinctive in its reddish-pinkish colour whereas Wilson’s Prom granite is lightish colour. This is because CQ granite is relatively uniform with biggish crystals of pink feldspar with a high potash content, while Wilson’ Prom granite has calcium rich feldspar. Granite consists mostly of quartz crystals and feldspar crystals.
How does all this come about? The centre of the earth is blazing hot – about 8,000°. The earth’s interior is not stable, because of the heat at the centre which is attempting to get out. Hot liquid is coming up, across the surface where it releases its heat energy and cools then goes down to that level again. It’s like snail racing though – it’s not happening any time quickly.
The surface of the earth is covered by tectonic plates and they are constantly moving. Even as you sit here you are moving northwards. Australia is still splitting away from Antarctica. When two plates collide there are three things that can happen:
1. Slide sideways along each other
2. Buckle and crumble up as in the Himalayas and Papua New Guinea
3. One can go under the other – subduction.
With subduction there is quite a bit of frictional heating and as the lower plate gets deeper into the earth there’s a lot of heat there anyway, so when the plate gets down about 30 km it starts to melt. When rocks melt they become lighter and rise – blobs of liquid hot rock forming and they rise up through the surrounding rock. If they rise far enough up to the surface they can even form a volcano which shoots off liquid lava up to the surface.
The plates are colliding in quite a few places around the world today: Japan, the Philippines, the Rocky Mountains, the Pacific Plate is going underneath America and Canada and that’s forcing things like Mt St Helen’s – various quite explosive volcanoes.
Subduction is a bit like a “lava lamp” where the blobs of oil rise up in the other liquid. If one of those blobs of liquid rock gets half way up through the surrounding rock and doesn’t get any further and sits there and cools down, it turns into granite. So granite is a symptom of this whole process of plates interacting with each other.
One example shown of CW granite had an inclusion in it. The technical word for this is “xenoliths”. “Xeno” means strange, as in “xenophobia”, and “litho” means rock. There is a type of granite at Wilson’s Prom called “xenoliths granite”. But they’re quite rare in CW granite which is why it’s preferred rock for quarrying because it’s very even. The xenoliths are pieces that have e fallen in from the outside. Pieces of the existing rock have fallen in from the roof and sides when the granite was molten and they get incorporated in the liquid mix like peas in pea soup. Then the whole lot turns solid. We can use these xenoliths to determine what sort of rock was there before the granite came up from deep down.
All this happened about 360 million years ago, according to the radioactive dating. There are about 150 outcrops of granite like that at CW scattered all over Victoria, and they’re all about the same age. That’s no coincidence; they were all caused by the same occurrence of some sort of plate going underneath Victoria. Didn’t happen before and it has never happened since, at least here in South Eastern Australia.
Gliddon, 1968 edition, p.77:
“A granite quarry was opened at CW in 1891 by Chambers and Clutten of Melbourne to supply stone for the Equitable Buildings in Collins Street. Captain Broomhead commanding this vessel (Kermandie) was in charge of transport arrangements at the beginning. The loading of these huge blocks of stone took advantage of the rise and fall of the tide which here is sometimes eleven feet (?). The vessel would be brought in on high water to the jetty built of granite to a point that revealed the tramline when the tide was out.”
They would dig the blocks of stone out of one place and tram them around a couple of hundred metres on these trolleys – a bit like the coal skips at Wonthaggi – and there they would load them on the boat.
“The trolleys on these rails brought stones from the nearby quarry to the ship’s side where a jib crane lifted them into the hold of the waiting vessel. When the return of high tide had refloated the ship the weighty cargo was conveyed to Little Dock at the foot of Spencer St Melbourne and stores for Phillip Island were loaded for the return trip. The voyage occupied two days and the load of stone shifted was about 50 tons.”
The quarry only operated for two years. 1891 and 1892. It is not a big quarry. There are at least three or four places where they quarried but in total they only took out less than enough rock to fill this room. It seems they abandoned it half way through and there would have been heaps of rock ready to go so people would have helped themselves like they did in Wonthaggi when the State Coal Mine closed. CW was a relatively small-scale, slow, hand-tools type quarrying.
From Gliddon again, p.137): “The CW granite has been used as a building stone in Melbourne. In the days when natural rock was the fashion for facing buildings it was found that the CW granite had many qualities ranking it amongst the best for such purposes. For standing up to the destructive effects of weathering this stone is particularly good. It does not contain substances that decompose readily to produce acids and unsightly ironstones.
“Although the colour of the CW granite varies from light to dark pink the polished stone is quite pleasing in appearance. It is handsome, weather resistant and ornamental, much darker in colour when polished than when left in the dressed but unpolished condition. Moreover it gives an extremely fine polish with relatively little work. Another useful property of this granite is its low capacity for absorbing water.”
It was handy that it was right on the beach and you could get shipping in there and transport it to Melbourne successfully. When you’re at CW quarry site you can often see rusted remains of the equipment used to split the hard granite into blocks of manageable size. These remnants are the evidence which tells us how the granite was actually quarried. Rows of holes were drilled across the rock, about an inch in diameter, possibly by hand percussion drilling although as John Jansson notes, power driven drills had been developed by that time. Each hole was then filled with a “plug and feather” to split the rock. This consists of two pieces of iron similar to a pipe cut in half longitudinally, placed into the hold, then an iron chisel “plug” pushed in between the “feathers” to prise the rock apart.
Once a row of holes were filled with plugs and feathers, the plugs would be hammered with a heavy hammer until the rock split. One of the interpretation signs at CW states that wooden dowels were pushed into the holes and used to split rocks open, working on the principle that the wood swelled when soaked in water. No evidence can be found at the site today to support this view, whereas several rusted sets of iron plugs and feathers can still be seen in position.
Evidence can also be seen, particularly at the quarry site adjacent to the former Aunt Sally Beacon, of the use of explosives to break out large rocks. Drill holes nearly two inches wide and radial cracking patterns in the rock show clearly that explosives were used when needed to work on selected blocks of granite. So while various aspects of the quarrying operation have been documented in Gliddon and elsewhere, the new information presented here tonight is the confirmation of the use of plugs and feathers, and explosives, in the workings at the site.
I would also like to quote John Jansson’s letter on the subject of the CW quarry:
“There were seven vessels used for carrying CW granite for the first contract for the Equitable building in Melbourne. 49 trips were made by these vessels from 27 May 1892 to 26 April 1893 with a total weight of about 2,000 tons of stone delivered.
The second contract was for 18 and 19 foot length blocks of around 14 tons used for columns etc. This stone was ready for transport in May 1893 and four possible trips were found to June 1893. The first trip on 27 May 1892 was done by the schooner Tyro belonging to local mariner Captain Lawrence Henderson. Henderson had been running the schooner Tyro for sawmill owner Alexander Stewart of Queensferry since 1877 and had bought it following Stewart’s death in 1888. He also owned the schooner Little Angelina and ketch Kermandie. He bought the Kermandie around the same time as the Tyro. In the mid 1890s Henderson built a sawmill, and the general store at Bass Landing, where he settled at his property called “The Landing”. He also ran a salt works for a while on French Island.
Another vessel used in this trade was the ketch Gertrude, 35 tons, with Master Captain Andrew Hannah. On its third trip it left Cape Woolamai on 26th June 1892. In port Phillip the cargo shifted while changing tack in rough weather, forcing the vessel onto her beam ends. The vessel then ran aground on Swan Point. It was later re-floated and repaired. A court of marine inquiry found the master guilty of failing to adequately secure the cargo with timber props.
“The Little Angelina did 30 trips from CW. The Kermandie did eight trips from CW under O J Broomhead. On the ninth trip another master Andrew Hendrikson took over, leaving CW on 7th December with 37 tons of granite in the hold and a bloc of ten tons on the deck. She proceeded to San Remo where she took on a cargo of wool. Bad weather forced her to shelter at Rhyll. She left Rhyll on 10th December against advice to stay due to threatening weather. Unfortunately the lessons of the Gertrude were not learnt as again the granite was not properly stowed. It is likely that she suffered a similar fate with the cargo shifting, causing her to sink.
“Stone blocks were split by drilling a row of one inch diameter holes about four inches depth and eight inches spacing. Steel plugs were inserted and steel feathers (wedges) were driven in to split the stone. It is not known whether holes were drilled by hand or were done with a compressed air drill. Compressed air drills were used on the Victor Harbour breakwater granite (South Australia) in the 1880s. About 50 men were employed at the granite quarry and a similar number at Messrs. P Finn and company’s polishing workshop in La Trobe Street, Melbourne.
“The stone was used for the bottom level walls and the columns of the Equitable Life Assurance building in Melbourne which was commenced in 1892 and opening in 1896. The upper levels used grey Harcourt granite.
“The Little Angelina did another trip in 1896 and 1898. This granite was probably for monumental use as it is recorded that Finn and Co had used Woolamai granite for this purpose some years prior to the start of the quarry.
“When the Equitable building was demolished in 1962 some pink Woolamai granite was apparently kept by Whelan the Wrecker as in later years blocks were obtained from there for some of the monuments erected on Phillip Island. The CW granite was probably much more valuable than the Harcourt grey granite and so was kept for re-use.”
References: Argus newspapers of 1892, 1893 and 1896. Diary of shipping movements in Cleelands Bight and San Remo kept by John Blake Cleeland. Scrap Book kept by John Blake Cleeland. Victorian geology excursion guide/editors Ian Clark, Barry Cook, G C Cochrane (technical editor)