Oparara Basin is one of the finest features of the Kahurangi National Park. The 35 million-year-old complex of limestone caves, arches and channels is popular with walkers, cavers and nature lovers. The Oparara Basin resides on a foundation of 350 million year old granite, which was covered with a 15-60m thin layer of limestone approximately 35 million years ago. The surface layer consists of blue-grey mudstone. The limestone layer has been extensively eroded by annual rainfall of up to 6m and the roots of the lush vegetation. Tectonic activity as well as changes in the level of the nearby sea have supported the appearance of unique geological formations. The basin currently contains many of the typical features found in a karst landscape, as well as some impressive rock arches and caves, and sites rich in limestone fossils.
1350 Mccallums Mill Rd, Kahurangi National Park 7073, New Zealand