The Moeraki Boulders are huge spherical rocks on Koekohe Beach on the Otago coast of New Zealand’s South Island. Appearing like a congregation of planets, the stones, with their sheer size and nearly perfect shapes, give birth to an alien landscape. Some of them remain partially encased by the surrounding cliffs, while others have completely revealed their beauty with patterned surface lines and colorful hollow cores. Maori legends provide one explanation of the boulders’ creation, while science proposes others. However, the awesomeness of these giant stones remains, and these geological mysteries of creation leave many people wondering exactly what they are and how they formed.
Moeraki Boulders on the beach in New Zealand. Source: Wikimedia, Pseudopanax, public domain.
Concretions of Beauty
People sometimes mistake the Moeraki Boulders for dinosaur eggs, alien remnants, or evidence of giants. Although their massive size and odd surface patterns are unique, round stones in nature are quite common. These are known as types of concretions which are mineral-cemented masses that often form within layers of sediment. The word ‘concretion’ comes from two Latin words. Crescere, means ‘to grow,’ and con, means ‘together.’ Hence, the stones are giant balls of sediments that have grown together over time in a process of cementation.
Most of the Otago concretions are round – some of them almost perfectly – while others are more ovoid or slightly irregular in shape. They range in size from about 1.5 meters to a little over 2 meters. Variably, they lie clumped in groups or as individuals scattered across the beach.
A number of the spheres are cracked and display a turtle-like mosaic.
The cracked surface of this Moeraki Boulder creates a geometric or turtle-back design. Source: Pixabay, public domain.
Before scientific inquiry, humans viewed the world and nature from a magical and wondrous perspective. Questions about the universe sparked colorful myths and legends that are still intriguing even today, and the Maori legend about the stones on the Otago Coast is no exception. One version of the story tells that long ago, the Kähui Tipua people sailed out on an expedition to the mythical land of Hawaiiki in their double-hulled waka (canoe) called the Arai Te Uru. Their goal was to find and bring back kumara sweet potato plants to grow back home.