Fjords and towering sea cliffs of Fiordland

Fiordland is in Te Wahipounamu – South West New Zealand World Heritage Area characterised by uplifted snowy mountains and deeply incised glacial valleys. There are 14 marine-flooded fjords, each 10-40 kilometers long with internal basins (200-420 meters deep) and shallow sills (40-120 meters deep) at their seaward mouths. The fjords were river valleys widened and deepened by glacial erosion during Quaternary glacial periods. The glaciers cut deeply into hard crystalline plutonic and metamorphic rocks that were once buried to depths of 10-30 kilometers. A mid-Cenozoic erosion surface has been uplifted in the last 7 Ma along the east side of the Australia-Pacific plate boundary (combination of eastward subduction and oblique dextral displacement at the southern end of the Alpine Fault). Glacial erosion of the uplifted surface has resulted in numerous sharp peaks rising from 1000 meters in the south to 2700 meters in the north. The west-flowing glaciers have carved classical straight, U-shaped valleys with spectacular glacially-striated vertical rock faces and numerous hanging tributary valleys and high waterfalls. Extreme rainfall gives Fiordland the name “Land of Waterfalls” and produces a thick freshwater layer on the surface of fjords. Post-glacial fjord sediments record switch from freshwater to marine environment (Dykstra, 2012).