Bore-ing! EarthCache

Pilliga Bore is part of the Great Artesian Basin, the largest and deepest freshwater basin in the world. The Basin lies underneath approximately one-fifth of the Australian continent, extending from Cape York to Dubbo. Here in north west NSW the waters are generally 38ºC.

Kamilaroi aboriginal people used the natural springs from the Great Artesian Basin as a source of water in times of drought. European settlers realised the potential of a reliable water supply for developing rural communities, the stock industry and enhancing the prosperity of agricultural production within the rich black soil of North West NSW. 

GEOLOGY

The water of the Great Artesian Basin is contained in several sandstone layers laid down by erosion during the Triassic, Jurassic and early Cretaceous periods (between 100 and 250 million years ago). During a time when much of Australia was below sea level the sandstone was then covered by an impermeable layer of mudstones and siltstones which formed a confining layer, trapping water in the sandstone aquifer.

The eastern edge of the Basin was uplifted when the Great Dividing Range was formed. The other side was created from the landforms of the Central Eastern Lowlands and the Great Western Plateau to the west. Uplift and erosion at the edges of the Basin exposed the permeable sandstone where rainwater was able to enter and slowly filter through to fill the aquifer. The Great Artesian Basin is replenished with water entering into the outcropping sandstone aquifers. This occurs mainly along the eastern edges of the Basin, especially along the western slopes of the Great Dividing Range (in NSW and Qld) and very gradually flows towards the south and west.

Artesian water is underground water, confined and pressurised within a porous and permeable geological formation. Natural pressure sends the water to the surface through an artesian bore.

To log the cache you need to answer the following questions and send them to 'Message This Owner' located at the top of the cache page. No need to wait for a reply, you can log your find at the same time. If there's a problem we'll get back to you. 

Please don't include answers in your log.

QUESTIONS

1. When were the Pillage Bore Baths constructed? (Now that the gate with the answer has been removed it can be found on the nearby sign)

2. What is an aquifer?

3. Observing the water in the bore pool, explain in your own words how artesian water is different to river water.

If you wish feel free to include a photo with your log of you or your team enjoying this precious natural resource.