Kahurangi is made up of different kinds of stones, from sediments, greywacke and meta greywacke (Haast schist) to karst/limestone mountains, and some parts volcanic rock. Some of New Zealand's oldest rocks and fossils were found here and date back around 350 to 500 million years ago. Kahurangi has several mineral sources such as magnesium, gold, pounamu (greenstone), coal and asbestos. The park's alpine landscapes have been shaped by glaciation millions of years ago.
Kahurangi contains several limestone caves, granite valleys, sandy beeches at Golden Bay, untouched rainforests on the western coastline, Te Waikoropua Springs and snowy mountaintops peaking up to 1875 m at Mount Owen. Rivers have created many gorges, valleys and arches as well as underground drainage and the cave systems that may cause sink and pot holes, fissures and beautiful rock formations.
The Golden Bay is located on the eastern side of Cape Farewell and is covered in sandy beaches from Port Popunga to Pohara. Behind the last of a few settlements, Collingwood, emerges a 26 km long land arm, the famous Farewell Spit. This peninsula is home for many of New Zealand's native and migrating bird species.
The Oparara Basin is one of the most famous granite valleys in New Zealand and contains the largest natural limestone arch in the southern hemisphere: The Oparara Arch. Measuring 220 m in length, this limestone formation clearly outdoes any of its sister arches such as the Moria Gate Arch which name was inspired through the Lord of the Rings trilogy.
Earthquakes such as the one on June 17, 1929, may also influence the formation of landscape. This earthquake caused the Karma River to gain a four kilometre-ling bulge.