Scattered along the beach at Moeraki are large, round rocks. These rock formations are technically calcite concretions that formed 65 million years ago. A concretion is a hard, compact mass of sedimentary rock formed by the precipitation of mineral cement within the spaces between the sediment grains.
The pearl-like growing process of the Moeraki Boulders formed as a result of the crystallization of calcium and carbonates around charged particles in the muddy undersea sediments. This process took as long as four million years creating boulders weighing as much as seven tons and measuring over 2 meters across.
During the Miocene period, about 15 million years ago, the seabed uplifted higher than the sea level. Since that time, waves, wind and rain have been excavating the harder calcite concretions one by one.
Or you could buy into the Maori legend explaining the boulders presence as the remains of calabashes (bottle shaped gourds), kumaras (similar to sweet potatoes) and eel baskets that washed ashore after the legendary canoe, the Araiteuru was wrecked at nearby Shag Point (or Matakaea in Maori). In Maori, the name Moeraki (Moerangi) means “drowsy day”.
Either way, these boulders are pretty cool to explore. As we were walking along the beach to get to the boulders, we were fortunate enough to see a dolphin playing in the waves. It was a single dolphin jumping out through the water in the same direction as we were walking.