Travels with Skis

Moeraki Boulders

There is this place on the south island of New Zealand, just north of Shag Point (yes, that is really what it is called), where they have these rocks which the locals call "The Moeraki Bolders". Now, I have no idea what Moeraki means (if I meet a Maori I will be sure to ask), but these things are seriously cool. Imagine that someone been playing boules using some seriously big rocks (about 2m in diameter), and then then just abandonded them on the beach mid-game - that is what the Moeraki Bolders look like. They are huge, almost perfectly spherical, and are just lying randomly on a beach in the middle of nowhere.



To satisfy the curious folk among you:

"The spherical boulders on the beach did not originate from bedrock in the way boulders normally do; they are concretions. The process by which the concretions are formed is not well understood, but it is similar to the way a perl forms around a particle in an oyster. The particle around which these boulders formed might have been a small fossil shell, a bone fragment, or even a scrap of wood.

The boulders are built up from a mineral called calcite. When they are exposed to the weathering effect of the sea, they lose their outer layers, and this leaves hard veins of crystallised calcite standing out in relief. As the weathering progresses the veins control the break-up of the boulder into small polygonal pieces.

A large concretion probably took about 4 million years to form."

So now you know.

posted by snow_gibbon @ 5:28 pm