As we drove through Lithgow, past the massive Wallerawang and Mt Piper power stations, and then were staying near the Ulan coal mines, naturally we spoke a lot about strategies for persuading the NSW Government to control the damage done to rivers and aquifers by coal mining.
The most famous geological feature in this area is "The Drip", a massive overhanging rock structure, about 200 metres long, at least 50 metres high. It was apparently formed by vertical jointing of the sandstone rock, which has ruptured open, allowing the Goulburn River to flow along this "crack" which is now some 200 metres wide. There is a parallel cliff face across the river, but not quite so spectacular.
The feature which earns this cliff the name is that half-way up the cliff there is a impervious layer of rock, an "aquitard". This layer prevents water in the sandstone rock above it from seeping down to lower layers, so, naturally, the water moves horizontally, under pressure from the water above this layer, and leaks out where the major vertical fault line has caused a cliff face.
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8 comments:
Magnificent country! Effects of the mines - disgraceful.
Hi Mick
Thanks.
The drying out is the main problem, for that will also risk killing the river, in the long term. Lets hope they can prevent the mine for coming closer.
It is wonderful country.
Cheers
Denis
G'day Denis,
Great post full of your usual informative detail. I've not heard the term 'aquitard' before - very apt. The pink is probably due to the inclusion of some iron oxide do you think? Some people pay big money for pink sandstone tiles I believe.
Regards,
Gouldiae
Hi Gouldiae.
Glad you got the meaning of Aquitard. It is a good word, especially when you can see a cliff with an obvious layer in it, which is leaking. A veritable geology text in front of you.
There is a lot of iron in the sandstone, but mostly it causes orange/brown staining. But it might be just a very gentle infusion of iron. I liked the colour, too.
Thanks
Denis
You can't baffle us southerners with long words Denis! Seriously, all the best with your endeavours.
Hi Duncan,
Aaw, Gee, Shucks, I thought I could put one over all youse country folks!
Cheers
Duncan.
hello Denis,
this particular area of the Goulburn River is indeed spectacular and special. I haven't got out to visit it for several years.
Your involvement in environmental preservation is a real credit to you. Our land is indeed fortunate to have dedicated people like you raising awareness and attempting to make a positive difference.
Well done.
Regards
Gaye
Thanks Gaye.
I had not been in this area for many years (not since starting to learn about coal and water issues).
However, there are some lovely features along the Goulburn River.
Fortunately, there are many locals who do value the River, and are fighting to protect it. But it is scary when you realise the Governments (State and Federal) are committed to expanding coal exports.
We need a total mind change - but that is a big ask!
Cheers
Denis
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