The Moeraki boulders are geological marvels. A group of over 50 large spherical boulders are strewn across the Koehohe Beach, some 75 km north of Dunedin.  They were originally formed as concretions in sea floor sediments and later gradually exposed through shoreline erosion. Their formation as septarian concretions (containing angular cracks) in mudstone took several million years and began about 60 million years ago. They are composed of calcite-cemented mud with veins of calcite, quartz or dolomite. Several processes (shrinkage, dehydration, expansion, fracturing, compaction) can be responsible for the precipitation from circulating solutions in the muddy host sediment. Maori legends tells that they are old calabashes and eel baskets that washed ashore after a legendary canoe Araiteuru was wrecked at nearby Shag Point.

Photos were taken at midday when storms were rolling in at high tide.

Shag Point/Matakaea is a nature reserve famous for diverse marine life viewing, interesting fauna, and is geologically fascinating. Flat rock platforms provide an easy haul-out site for seals, breeding for seabirds, while whales and dolphins are active offshore. Rare lilies, snow tussock and other alpine species grow here while the rock shore is lined with rimurapa bull kelp and dense forests of giant bladder kelp are just offshore.

Skeletons and artefacts provide evidence that the Matakaea area was used by early Mao hunters, dating back to the 12th century. The name is linked with Arai Te Uru canoe, which capsized off Moeraki. The crew managed to swim, leaving the cargo to wash ashore (Moeraki boulders). They fled inland and were transformed into mountains.

Large round boulders are embedded in the soft colourful sandstone, which is rich of fossils including a 7m marine reptile, a plesiosaur, which is now part of the University of Otago fossil collection. Whalers discovered the first bituminous coal here in the 1830s. Since mid 19th century, exposed coal seams were successfully mined until 1972, leaving many caves and shafts that extended under the coast.  A small natural boat harbour was once a traditional tauraka wake (canoe landing place), then used by miners shipping coal in sailing and steam colliers. Today the harbour is used by recreational anglers and divers to launch their boats (Source: information from DOC.govt.nz).