Colquhoun Quarry EarthCache
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Ideally you should visit this EarthCache before visiting “The Entrance at Lakes Entrance” EarthCache.
To get to the site, turn off the Princes Hwy at the “Log Crossing Picnic Area” sign (not far from Forestech). If you head to the right you will pass the picnic area (there used to be a cache there) & you can even walk to the quarry from there, but it is a 7.4km walk! Even though you might not choose to walk the entire 7.4km, it is definitely worth your while to cross the bridge and take a short loop walk at the start of the track. There you will find remnants of the quarry tramline, together with several large granite boulders that were rumoured to have fallen off the very last rail journey because the workmen were in such a hurry to get to the pub before it closed!
I suggest you then drive on to Quarry Road, off Uncles Rd and park at:
S37 46.906 E147 55.733 – from there the walk is only 120m.
This granite quarry was opened in 1904 to provide rock to reinforce the man-made entrance to the Gippsland Lakes (see other EarthCache listing). Two interpretive signs at the quarry site provide details on how the granite was taken from the quarry and then shipped to the entrance. A tramline was built to transport the rock 13km from the quarry site along the Mississippi Creek to barges at the head of the North Arm inlet. The barges then took the rock a further 6km to the entrance site.
Once the entrance was completed granite was later taken to Melbourne for other building purposes. The quarry ceased production in the 1940s.
A bit about granite:
Granite is a type of igneous rock, which is formed from melts in the Earth's crust. Igneous rocks are classified using grain size, silica content and/or silica saturation.
Grain size reflects the depth at which the molten rocks form in the Earth:
- Volcanic rocks form close to the surface, cool quickly and form fine grains/crystals.
- Sub-volcanic rocks form at intermediate depths, generally in dykes (vertical sheet of intrusive igneous rock) or sills (horizontal sheet of intrusive igneous rock) and form medium grains.
- Plutonic rocks form deep in the Earth, cool slowly and form coarse grained rocks.
Granite is the most common type of plutonic rock. Granite is a very strong and durable rock, which makes it ideal for construction purposes, and the coarse grains of different colours make granite so beautiful when polished.
To log your visit you will need to message me (through the geocaching message centre only please) the following:
1. The colour of the granite mined at this site.
2. The estimated height of the quarry walls.
(A rough estimate is OK, but if you feel compelled, you can walk up the steep marked track behind the quarry to get a GPS reading – but beware, getting an accurate GPSr in the forest can be challenging!)
I am happy for you to log your visit in anticipation of my confirmation; however, if I do not receive your email with the correct information I will be obliged to delete your log.
Your log should include the number of people in your party. Photos are encouraged but not essential. Obviously your log, including any photos, should not give away either of the answers.
For further information on igneous rock formation visit the Australian Museum Online at http://www.amonline.net.au/geoscience/earth/igneousclass.htm
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