WORLD OLDEST CAVE

 relentlessly changing over millions of years, a vast coral reef compressed into limestone, the limestone rose out of the ocean and became part of a high mountain range.  The action of water carved caves out of the limestone. Clouds of volcanic ash, containing potassium, settled in the caves and crystalised into clay minerals.  Some of the potassium was radioactive, and began changing to Argon gas. The gas remained trapped in the crystalised clay minerals.  All these changes took many millions of years.

Fast forward to 2005. Using X-ray diffraction and scanning electron microscope imaging, the Australian Museum identified eight clay areas in the Jenolan Caves that were suitable for dating – areas where the Argon gas atoms could still be trapped.  Knowing that it takes 1,250 million years for all the potassium isotopes to change into Argon, the CSIRO scientists used a variation of potassium-argon dating to work out the age of the clay minerals. They could tell that the clay was 340 million years old, and had to have been deposited in the caves after the caves were formed. This work was done by the CSIRO’s Petroleum Resources division, using a technique they developed previously to help oil exploration companies find oil deposits. It is a good example of how industry-focused techniques can be used to solve geological mysteries. And see how it’s all about constant change?