Moeraki Boulders
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The Moeraki Boulders are unusually large spherical boulders lying along a stretch of Koekohe Beach on the wave-cut Otago coast of New Zealand between Moeraki and Hampden. They occur scattered either a
Boulders of varying sphericity broaching the Otago coast
The boulders at sunrise
A cracked boulder displaying its hollow interior
Concretion
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A concretion is a hard and compact mass formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. Concretions are often ovoid or sphe
Moeraki Boulders
…as isolated or clusters of boulders within a stretch of beach where they have been protected in a scientific reserve. These boulders are grey-coloured septarian concretions, which have been exhumed from the mudstone and bedrock enclosing them and concentrated on the beach by coastal erosion. Especially in recent years, the…
Concretions in Torysh, Western Kazakhstan
Concretions with lenticular shapes from an island in the Vltava river, Prague, Czech Republic
Marlstone aggregate concretion, Sault Ste. Marie, Michigan, United States
Concretion rock with white core from the Middle Jurassic of Iran