The story of Magnetic Island began 275 million years ago when molten granite was pushed to the earth’s surface with volcanic force. Over time the overlying volcanic rocks weathered away. The underlying granite mass has decomposed along fracture lines, creating today's extraordinary landscape of rounded domes and boulders (tors), many of which are larger than a house and spectacularly perched.
Hawkings Point Lookout sits atop of a huge granite tor and offers spectacular views over Picnic Bay and towards Townsville to the south west and Rocky Bay, Nelly Bay and Geoffrey Bay to the north east.
Granite is composed of between 20-60 percent quartz (silicon dioxide), lots of feldspar (a family of silicate minerals) and then a selection of other minerals which give it different darknesses and textures.
The crystals of feldspar and quartz which make up the majority of granite are sensitive to the Earth’s magnetic field (the magnetosphere) as they cool. Once they have solidified they contain a snapshot of the polarity and intensity of the magnetosphere. Provided the rocks aren’t contaminated by heat at a later date they can be used to read the strength of the Earth’s magnetic field dating back billions of years. This same phenomenon may have been experienced by Lt James Cook in 1770 when he believed that the magnetic compass on his ship the Endeavour was affected by the island and the reason why Magnetic Island came to be named.
Permission has been granted by the Queensland Parks and Wildlife Services (QPWS). All standard rules and regulations must be complied with inside the National Park. The Ranger-In-Charge encourages all Cachers to ‘Be Pest Free’ and remain on the track and within the lookout barriers. NPWS Alerts
To claim this Earthcache:
1. Explain in simple terms how weathering formed the tor that you are standing on.
2. Estimate the diameter of the tor you are standing on.
3. Describe the granite you are standing on - texture, size of grains, colour.
4. What is the term given to the study of the polarity and intensity of the magnetosphere?
Optional but appreciated, take a photo of yourself at the lookout.
You may log your visit immediately however please message (not email) the C.O. within a week of your log with your answers otherwise your log may be deleted.
Congratulations to Gabba2 for being the FTF.
