Welcome to one of the most impressive small-town memorials we have ever seen, we hope you are as equally impressed, while you are here don’t forget to check out Temingi’s virtual nearby GC88ZAY .
Australia is getting smaller, meanwhile China is getting bigger! - well there is a statement that is likely to trigger a few passionate Aussies. To find out why Australia is getting smaller and China bigger we need to look closely at Capricorn Sandstone’s quarry in Stanwell (Ref point 1). It is one of the largest sandstone quarries in Australia, uniquely producing landscape through to restoration grade sandstone in a variety of colours. Sandstone has been quarried from Stanwell since the late 1800s, and there are many fine buildings throughout Australia built that feature this lovely natural stone. Interestingly enough, there is a lot of Chinese sandstone imported to Australia, while the Australian sandstone exported back into China and is considered a luxury item.
It is not practical for you to visit the quarry site, so this unique display is the next best thing.
What makes our Sandstone so luxurious? The short answer is it is very high quality, Sandstone is rated on quality, price and then colour specifics, Capricorn Sandstone is at the high end in all those categories.
Officially Capricorn sandstone is described as a medium grained, composed of a framework of quartz and altered felsic (rich in elements that form feldspar and quartz) volcanic rock grains, set in a binder of secondary silica (sand) and goethite (and a clay matrix, mineral consisting of hydrated iron oxide) which gives the stone its hardness and durability. There are two main colourings in the Australian market: Capricorn Buff and Heritage Rose. Capricorn Buff is very similar to the Sydney sandstone from which many historical buildings are built and is therefore popular with Restorers and Architects.
The Capricorn deposit of Sandstone is situated near the top of the cliff which is a part of Queensland’s Jurassic Razorback beds. The razorback beds outcrop sporadically between Stanwell and Mount Morgan. The lower part of this deposit is composed dominantly of massive quartzose sandstone with rare cross stratification (layering) together with lesser conglomerate, claystone, and siltstone. The other 2/3 is composed of thinly bedded and cross stratified sandstone with silty interbeds and claystone laminate. The thickness of the unit average is 45 m. The razorback beds are a freshwater deposit, the present presents of claystone and general absence of cross bedding in the lower part of the unit suggests a lacustrine environment (lake). The rare cross stratified sections of the upper part of the unit suggest a fluvial (flowing) environment. The dips (shape) of the cross stratification indicate that the currents flowed in a northwest direction in the Capricorn quarry area. The sequence consists of basal (bottom) siltstone unit with a broad, regular Flaggy (splitting or tending to split into layers) Cleavage (tendency of a mineral to break along smooth planes). There are very few joints and other fractures present in the stone, fossilised twigs, and leaves occur sporadically throughout the sandstone this is called ‘Tea-leaf’, there are also some dark red brown ironstone concretions these are also known as kidney stones in the stone trade.
The odd shapes of concretions arouse curiosity, and they can often be mistaken for fossils, bones, meteorites, or other unusual objects. Concretions can have regular shapes like blocks, boxes, pipes, flat discs, canon balls, or even resemble parts of a human body such as a foot or rib.
To make ironstone concretions, ground water dissolves iron compounds from the inner portion of a block, then deposits them again as insoluble iron oxide in the outer parts, cementing together grains in the original rock to make that area harder. There is often brown, yellow, or red concentric (shapes which share the same centre, usually circular) ironstone banding within the block. This process goes on only while the rock is below the ground water level, but when this level drops, drying and oxidation takes place.
To log this Earthcache we require you to visit GZ and the listed waypoint to make some observations, consider the information given, then message us with the following answers to the best of your ability.
1. Do you think the sandstone here is Capricorn Buff and Heritage Rose? In your answer explain why.
2. Facing the manmade sandstone wall in front of you, there is an obvious feature in the Sandstone that was mentioned in the earth science lesson, can you identify what it is, describe its colour and shape.
3. Head to WP2, along the way, observe the sandstone blocks, looking for the same type of feature you identified in Q2, are they frequent or infrequent, does the shape and size vary, are there any at GZ?
4. A photo of your team or GPS nearby without giving the answers away.
You are welcome to log your find straight away to keep your TB's and Stats in order but please message us with your answers within a couple of days. Cachers who do not fulfil this Earth Cache requirement will have their logs deleted without notice.