Niddrie Quarry (Earthcache) EarthCache
Niddrie Quarry (Earthcache)
-
Difficulty:
-
-
Terrain:
-
Size: 
(not chosen)
Please note Use of geocaching.com services is subject to the terms and conditions
in our disclaimer.
This site demonstrates a number of geological stories.
The first is the tale of the volcanic eruptions that formed the
bluestone planes of Western Melbourne.
The second relates to the visable impact of mining basalt in order
to supply chip for road production.
The third relates to geotechnical engineering and the stabalisation
of the quarry cliff face.
The Niddrie quarry was formed in the 1940s to extract basalt for
road paving from the vast lava plain that stretches from Melbourne
to Mount Gambier. Quarry operations continued from 1940 right
through to 1975, when the privately owned quarry was eventually
closed. The land laide derelect for many years unitil the decision
was eventually made to stabalise the site and turn it into a
residential subdivision.
The bluestone that was mined from this quarry is part of a massive
sheet of basalt that was formed from molten lava that flowed from
active vents and cooled to form the surrounding Keilor
Plains.
The basalt from the quarry is about four and a half million years
old (erupted in the Pliocene period) and is thought to have
originated from Crowe Hill, near Mickleham, although the
surrounding plain has been formed by lava from at least 37 seperate
lava flows.
Basalt is the most comon rock formation in the solar system and on
the surface of the earth. Basalt is mafic, that is, it contains
relatively little silica: about 50% by weight. It is usually dark
grey but can also be green, brown, or black. Its essential
constituent minerals are calcium-rich feldspar, and calcium- and
magnesium-rich pyroxene as well as olivine (which can come in iron
and magnesium rich varieties).
In order to log this cache you must answer the following
questions.
It is hoped that the process of answering the questions will allow
you to learn a little about geology (the morphology of basalt - and
in doing so where to find information on the morphology of other
rocks) and a little about the geotechinical engineering techniques
used to stabilise this quarry site.
1. Describe the structure of the basalt. Is it column shaped,
pillow shaped, frothy, solid etc. What colour is it?
And now for some independant learning...
2. Researching basalt (using your answers from the question above)
would you expect that this basalt erupted in open air or under
water?
3. Researching the geotechnical engineering work that has been used
to stabalise the quarry wall, how many square meters rockfall mesh
were used?
4. What's special about the rock fall mesh that was used compared
to normal wire mesh?
5. What is the altitude (according
to your GPS) of the quarry lake?
Note that you should email this information tio the cache owner.
Please do not include it in your cache log.
Additional Hints
(Decrypt)
Jvxvcrqvn vf lbhe sevraq