This is the world of the caver, as beautiful, alien and remote as the glaciers on high mountains. And just as mountaineers are tempted by summits that rise far above familiar ground, caverns are drawn into a subterranean wilderness every bit as exciting as any place warmed by the rays of the sun. There are thousands of caves in Australia. Some are at the edge of the sea, carved by the erosion of the waves, while others are lava tubes created when the surfaces of rivers of molten rock cooled even as the lava beneath continued to flow. Most caves, however, were formed as rainwater, made slightly acidic by carbon dioxide in the atmosphere and chemicals in the soil over which it ran, seeped into fissures in soluble limestone and gradually, over thousands of years, melted out branching networks of tunnels and rooms.
Some caves are too tiny to enter, while others are many kilometers in length.
Within some caves are chambers larger than the biggest sporting arenas, and shafts deeper than the tallest buildings. There are towering pillars, and expanses of colorful stone folded as if they were massive draperies. The forces that build a cave work with infinite patience. A drop of water hanging from the point of a stalactite leaves a trace of mineral residue when it falls, lengthening the stalactite ever so slightly. Scouting works the same way.