This is an earthcache, there is no container to find, you have to read some geological information, visit the site and supply the answers below and log the find online.
To get to the listed coordinates, head to the top of Mt Stuart, park in the public carparks and wallk down to the cache. Looking away from Mt Stuart Road you should be facing fencing and communication buildings, car on right, low cutting with exposed rock on the left. At the listed coordinates look at the low cutting on the uphill side of the access road. There are a couple of exposed rock surfaces, a sloping broadly rectanglular one and a few more more vertical jagged ones. Closely inspect the broadly rectangular rock face that tapers slightly to the ground. An obilque helper photo is attached, the red circle is where the coordinates were taken, the yellow arrow points to the rock to view.
This earthcache is near the top of Mt Stuart, where the rocks are types of hard granite that formed from molten rock (magma) underground under heat and pressure over 250 millions years ago. This did not all happen at once and at this particular location there has been a combination of different magmas, possibly over millions of years. A geological 'instrusion' forms where magma is pushed from deep within the earth into any cracks or spaces, sometimes existing rocks can be pushed out of the way as well. This earth cache highlights several intrusions of microgranites. Microgranites have smaller grains than regular granites.
At the exposed rock face one molten rock has intruded into, or around another rock and creating a mix of 2 rock types. 'Xenoliths' have formed as a result of the intrusion(s). The term 'xenolith' applies to foreign rocks encased in another igneous rock. In this case a microgranite rock is surrounded by a different microgranite rock. This mixing has resulted in the exposed rock face having a blotchy or blob like appearance. In this mix are 2 rocks types;
One of the rocks is described as 'micromonzonites'. This is moslty a light brown colour and no obvious flecks. Call this one rock A.
Rock B is described as a light grey microgranite with numerous white feldspar crystals. Feldspars contain silica based crystal.
The observant earth cacher may note the occassional black rim, that is a reaction between the xenolith and the surrrounding layer.
You should also note that one side of the exposed rock face has a straight section like a light coloured border. Magma can also intrude as a vertical sheet, this is known as a 'dyke'. This outcop is also cut by a vertical vein (dyke) a couple of centimetres wide, of an even lighter coloured microgranite called aplite, call this rock C.
1) Consider which rock (A or B) forms blobs up to 20 cm surrounded by the other rock. Is the blob xenolith rock A (light brown) or B (grey with white crystals)?
2) Given number 1 then the rock surrounding the xenolith must be the other one, rock A or B?
3) Locate a feature matching the description of light coloured aplite rock C on the broadly rectangular rock face. Looking from the access road is it on the botton left or top right of the larger area of exposed xenoliths?
4) What feature do you think the magma filled to form the aplite dyke?
5) Include a photo of the rock face in the message centre. If you have the technology you have the option of answering Q1-3 by annotating the photo (fine if you don't - just send answers). Please don't post photos of the rock with your cache log.
Send your answers, one per team in the message centre or via email and log it online when convenient. Online logs with no answers or doubts over attending the site will be queried and may be deleted.
Information is taken from Parks and Landscapes of the National Parks of North Queensland by W. Willmott (2009) and Rocks and Landscapes of the Townsville District by D.L. Trezise and P.J Stephenson (1990). D. Trezise contributed to the Townsville sections of the book by W. Willmott.
The cache background picture is from a different xenolith intrusion just down the road a bit.