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Mysterious Caves

This large cave has been eroded through limestone deposits by the Oparara River near Karamea. Image: Julian Thomson.

This large cave has been eroded through limestone deposits by the Oparara River near Karamea. Image: Julian Thomson.

New Zealand has spectacular limestone (karst) landforms including northwest Nelson and the Buller Region (West Coast) as well as in the Waitomo area of the North Island.

Karst landforms are formed by the slow dissolution of limestone or marble bedrock by slightly acidic groundwater. This process gives rise to curiously pocked and sculpted landscapes and deep underground caves with spectacular formations. New Zealand has some world class cave systems that are actively being explored by cavers who often spend multiple days underground.

Caves
Groundwater is usually slightly acidic, and slowly dissolves cavities into the limestone bedrock to create underground tunnels and passages. As the water cuts ever deeper pathways through the rock, it leaves behind drier passages at higher levels.

Hollywood Cave 4. Image: Neil Silverwood.

Image: Neil Silverwood.

Stalagmites and stalactites
When this carbonate rich water flows across the cave walls, it partially evaporates, and leaves small amounts of calcium carbonate on the surface to form a fantastic variety of curtains, pillars, stalactites and stalagmites as well as straws, crystals and even cave pearls!.

View more images in the Gallery.