I went to Mudgee over the weekend, with fellow Rivers SOS members, for a strategy meeting.
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."The Drip" is not particularly wet now. It seems it is drying out, owing to coal mining which is occurring some hundreds of metres away from this extraordinary feature.
A few hundred metres downstream from "The Drip" is the "Mini Drip". It is in good condition, with a magnificent layer of ferns growing out of the leaking layer.
Here it is again, looking downstream.
On the way back downstream from "The Drip" I noticed this beautiful and unusual sandstone rock, which had cracked off a much larger rock, which itself had fallen from a cliff face above. I was taken by the delicate pinkish colouration in the rock.
Unfortunately, large pieces of coal get washed down the Goulburn River, from the Ulan Mine. It seems the river has been diverted around the edge of the open cut mine, some 5 Kms away from this spot. However, here is evidence of large chunks of coal being washed down the river.