Achernar and Bohemia caves - New Zealand

Achernar (1.540 m long and - 252 m deep) and Bohemia (3.170 m long and -386,+7 m deep) Caves are located in the alpine karst region of Mt. Owen, Northwest Nelson, South Island, New Zealand.

These two cave systems consist of fossil passages meanders, shallow shafts and large chambers. In particular, Bohemia Cave has the largest chamber in New Zealand.

The caves mostly developed along bedding planes in the metamorphosed carbonates of the Upper Ordovician Arthur Marble. However, the largest chambers formed at the cootact between marbles and underlying phyllites.

Cave interior deposits are locally represented by clastic sediments. Speleothems are the most interesting features because of the presence of excentric deposits of aragonite, calcite, hydromagnesite and gypsum.

The two caves mostly developed over a long period of time characterized by quite tectonic setting, possibly in Pre-Pliocene.

In the course of the tectonic uplift of the area, streams cut through the underlying basement. Pleistocene glaeier melting waters accelerated the entrenchment of meanders, enlargement of chambers and destruction of gravel terraces.