Moruya Granite Quarry
The Moruya Quarry, also known as Government Quarry, was first opened in 1876. Located on the northern bank of the Moruya River, its great claim to fame was providing the stone for the piers and pylons of the Sydney Harbour Bridge.
The quarry was chosen to supply the stone because of its proximity to the river made it ideal for loading the barges with the blocks of granite, one of which weighed over 20 ton.
Work began in 1925 and continued for seven years. During this time there were 250 men of 13 nationalities on the payroll of the contractor, Dorman Long & Co. A township of 300 people sprang up at the quarry and was aptly named Granitetown. There were 67 cottages, bachelors` quarters, quarters for the Italians, a post office, co-operative store, school and hall.
John Gilmore was the quarry manager responsible for every block of granite in the bridge, each of which was hewn, cut, dressed and arranged into position to then be numbered before shipment like a jigsaw puzzle. Not one stone was rejected.
He was also responsible for directing workers as the cut, dressed and inscribed the Cenotaph Stone for Martin Place in Sydney in 1927.
In 1931, the work drew to an end as the job was complete. In that time, the quarry produced 18,000 cubic metres of dimension stone, 173,000 blocks and 200,000 yards of crushed stone that was used for concrete.
The rock is very strong, dense and fine grained and was quarried from the site for 100 years for building blocks, kerb stones, railway ballast and road surface from several quarry sites.
The remains of the quarry are across the road from this EarthCache but remnants of the old wharves remain near GZ along with many samples of the famous rock.
Geology
Moruya Granite is the commercial name for stone that was quarried during the 1920’s near Moruya on the New South Wales south coast and transported by steamer to Sydney Harbour for the construction of the pylons of the Sydney Harbour Bridge. At least one barge used in the transport is now half submerged on the banks of the north side of the Moruya River. Hundreds of tourists now climb up the Harbour Bridge pylons every day to get a magnificent view of Sydney Harbour from the top of the bridge steel arches.
The geological name of the rock is Moruya Tonalite, a rock unit within the Moruya Suite of rocks comprising six north-south-trending elongate granite plutons at the extreme eastern side of the Bega Batholith.
These rocks were emplaced at a few kilometres depth within the Earth’s crust during the Middle to Late Devonian geological period. Subsequent erosion has exposed them at the surface.
The Earthcache
In order to log this Earthcache, you'll need to answer the following questions and email your answers. Feel free to log your find in anticipation- I'll let you know if there are any issues. Logs without the emailed answers may be deleted. It is also preferable that you upload a picture of you/ your group and your GPSr at the EarthCache with your log.
At GZ you'll find a rotunda of sorts with plenty of information boards. Read the boards and find the answers to the following questions:
1. The pylons and piers of the Sydney Harbour Bridge were faced with how many cubic metres of the granite from this site?
2. The stone for the Cenotaph in Martin Place, Sydney also came from here. The Cenotaph base block is how long and wide?
Venture nearby to a block of granite at around S 35 54.259 E 150 06.857. ***Update 31/12/22- this block is still fine to view but since the EarthCache was created things are a lot more overgrown.***
3. What is the approximate size of this piece of granite?
4. What size are the grains of the rock? a) around 1mm? b) 1-2mm, c) 2-5mm, d) 5mm plus?
5. What colours can you see in the rock?
6. How many drill grooves are there on the top of the western face of the block? ***Update 31/2/22- you could almost call this the north side- the side closest to the path in any event.***
References:
www.nationalrockgarden.org.au
http://monumentaustralia.org.au/themes/technology/industry/display/22205-moruya-granite
