On this extreme South West corner of the continent, the earth has thrust up a wedge of granite rock, cracked from the edge of the continent, to form this distinctive “chin” on the face of Western Australia.
For millions of years this “chip off the old block” lay beneath the Southern and Indian Ocean confluence; as billions of tonnes of fossilised marine skeletons draped its granite back with a blanket of limestone.
After the Leeuwin-Naturaliste Ridge was upthrust, Mother Nature filled the intervening gap with precious fresh-water-holding sandstone aquifers and covered it with forest-enriched topsoils . Then, over millions of years, geological stress caused by the “chip” continuing to drift away from the “block” has fractured the intervening sandstones with a number of vertical faults.
Through these faults, fresh water circulates from the surface to refill the aquifers and later recycles to the surface through underground springs to replenish the rivers.
This is how the CSIRO illustrated water flows through the aquifers of the central Perth Basin. In the southern section, on the Margaret River, the Leederville aquifer comes to the surface to refresh a number of perennial pools.
The proposed coal mine will have to penetrate through the Leederville aquifer- a plan that mining engineers have assessed as “highly dangerous” with catastrophic risks attached.
Any disruption to the aquifer could have disastrous implications for the local surface water and the wider underground systems.