Please note to successfully complete this Earth Cache you will need to be at beach level looking up, you will need to touch the surrounding earth. Access can be made at either end of the cliffs during daylight hours only (see reference points and suggested parking points), there are short steep goat type tracks that can be used (our 5 y o coped with these) if you are less confident you can use a flatter access point (see reference point) but you are in for a longer walk.
This cache may be harder to complete at absolute high tide but not impossible, if you would like to check the tides before you go You can Click here to check tide times at Port Augusta.
This Earth Cache will take you to the spectacular Red Banks, there are already a few traditional caches in the area but we thought it would be nice to take you down to see the cliffs close up and give you some basic understanding of what you are looking at without giving you pages and pages of scientific jargon.
Basically, you're looking at ancient alluvial fan draining the uplifted Flinders Ranges. The sand-silt-clay layers are rich in iron oxides (hence the red colours) and the groundwater is saturated with limestone with crystals of gypsum (calcium sulphate hydrate). We were fascinated with the decorative shapes and patterns of Gypsum present in the area.
What is an Alluvial Fan? Once near GZ you will be standing in one! An alluvial fan is a fan- or cone-shaped deposit of sediment crossed and built up by streams. If a fan is built up by debris flows it is properly called a debris cone or colluvial fan. These flows come from a single point source at the apex of the fan, and over time move to occupy many positions on the fan surface. Fans are typically found where a canyon draining from mountainous terrain emerges out onto a flatter plain, and especially along fault-bounded mountain fronts.
What is uplift? Uplift, in geology, vertical elevation of the Earth’s surface in response to natural causes. Broad, relatively slow and gentle uplift is termed warping, or epeirogeny, in contrast to the more concentrated and severe orogeny, the uplift associated with earthquakes and mountain building.
What is Iron Oxide? Iron oxides are chemical compounds composed of iron and oxygen. All together, there are sixteen known iron oxides and oxyhydroxides.
Iron oxides and oxide-hydroxides are widespread in nature, play an important role in many geological and biological processes, and are widely used by humans, e.g., as iron ores, pigments, catalysts, in thermite and haemoglobin. Common rust is a form of iron oxide.
What is Gypsum? Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. It is widely mined and is used as a fertilizer, and as the main constituent in many forms of plaster, blackboard chalk and wallboard.
We hope you enjoyed the area and perhaps you even learnt something?
To log this Earth Cache we require you to consider the information presented to you in this Earth Cache, walk along the beach not just at GZ and look at the area, perhaps you will need to do some research of your own, then message us with the following answers to the best of your ability;
1. From your chosen vantage point, what colour is most prevalent? Why is it this colour?
2. As you move along the beach feel the wall and feel the floor, is there a difference? Why do you think there is or isn’t a difference?
3.Can you find any Gypsum, describe the shape, size, colour and texture, is there a lot of it?
4. Can you find any horizontal layers in the cliffs, what do you think has caused this?
5. A photo of your team or GPS with the sands in the background, upload as many photos as you like we would love to see the area again and again. (Optional)
You are welcome to log your answers straight away to keep your TB's and Stats in order but please message us with your answers within 24 hours. Cachers who do not fulfil the Earth Cache requirement will have their logs deleted.
Source: Dr V.A. Gostin, Wikipedia, Encyclopaedia Britannica.