Honeysuckle Creek Tracking Station EarthCache
Honeysuckle Creek Tracking Station
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Namadgi National Park is 105 900 hectares, making up more than half of the Australian Capital Territory. Namadgi was declared in 1984 protecting all animals, plants and cultural sites.
The oldest exposed rocks in the Namadgi area are sedimentary sandstone, mudstone and shale. These were deposited between 470 and 440 million years ago during the Ordovician Period. They contain the remains of small marine animals called graptolites, which indicate that the sediments were deposited in fairly deep seawater not close to land. At that time most of southeastern Australia was under the sea.
Towards the end of the Silurian period, approximately 400 million years ago, the area we now know as Namadgi was intruded by a huge body of granite known as the Murrumbidgee Batholith. The many fantastic granite boulder formations that are to be found in the Park resulted from this intrusion.
There were major earth movements throughout the whole of southeastern Australia between 400 and 350 million years ago. Rocks were folded and raised into high mountains and since then the Namadgi area has not been below the sea.
The sedimentary rock overlaying the granite has now worn away, exposing the weathered granite boulders seen today.
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.
The granite boulders surrounding the posted coordinates are spectacular, but not unique to this part of the park. Numerous hiking trails and caching adventures in Namadgi will show you lots of examples of the geology of the area. However, this site will also show you a lesser known part of Canberra's link to space exploration - the Honeysuckle Creek Tracking Station. To find out more, take the short Apollo Walk and discover some more of Canberra's history.
17 March 2007 marks the 40th Anniversary of the opening of Honeysuckle Creek Tracking Station. It was officially opened in 1967 by the Prime Minister of the day, Harold Holt.
To claim this EarthCache message me (through the geocaching message centre only please) the answers to the following three questions:
1. What is the height above sea level at the listed coordinates (start of the Apollo Walk)? Imagine the immensity of the earth movement and subsequent erosion that has occurred to bring this rock to the surface at such an elevation!
2. Find the time line on the display - what is said to have happened around 60,000 years ago?
3. Find one of the large granite boulders surrounding the site & look at the different coloured crystals - what are three (3) of the colours you can see? (Bonus points if you can name the different minerals/crystals.)
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 indicate how many people were in your party and include something interesting that you learned on the Apollo Walk. A photo of your visit to this picturesque area is also required. Obviously your log, including any photos, should not give away either of the answers.
Sources:
http://www.honeysucklecreek.net/index1.html
http://www.australianalps.deh.gov.au/parks/namadgi.html
http://www.amonline.net.au/geoscience/earth/igneousclass.htm
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