 Moeraki Beach (31.2KB) |
 Derek on one of the boulders (39.2KB) |
 Laurie's balancing act (51.5KB) |
 Closeup of eroding concretion boulder (30.8KB) |
Moeraki Beach lies on the east coast of New Zealand's south island, about 45 km north of Dunedin. According to the Lonely Planet guide, geologists refer to these boulders as "septarian concretions," formed by minerals crystallizing equally in all directions from nuclei of organic material. They eroded from the nearby mudstone cliffs, and eventually disintegrate into pieces, as you can see below. I think the inside is calcite, but I can't remember for sure. The guide also says that two concretions have been found to contain the bones of a 7-meter plesiosaur and a smaller mosasaur.
Moeraki Beach (31.2KB) |
Derek on one of the boulders (39.2KB) |
Laurie's balancing act (51.5KB) |
Closeup of eroding concretion boulder (30.8KB) |