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Monday, 4 January 2010

Caves and Moa Bones

Takaka limestone landscape
On a recent trip up Takaka Hill near Nelson, I went exploring over the limestone landscape with my daughter Sophie (with permission from the landowner). The area is riddled with sink holes and caves. The most well known is Harwood's Hole - a huge vertical shaft about 50 metres across and over 180 metres deep. However most of them are much smaller - many only a few metres deep and blocked with debris.


Moa Trap - the cave entrance
In this second picture you can see a typical example. A small cave entrance half concealed by vegetation. Inside it, a few metres from the surface and half buried in the clay floor Sophie discovered a moa bone . With a bit of digging we eventually uncovered a variety of bones from several individual skeletons. They were jumbled up with blocks of rockfall debris and many of them were covered in a thick layer of white cave deposit (calcite). This showed that they were likely to be pre - ice age (at least 70 thousand years old) as it takes a long time for the bones to become coated in this way.
Finding a moa bone

There were once atleast 9 species of moa in New Zealand, although only two of them were common on Takaka Hill. The limestone pot holes were a death trap for many that fell in and were unable to escape.

The bone that Sophie is holding in the picture is a lower leg bone (metatarsus).

If you would like to see the bones, they are now resident in Ngarua Cave. This is a very worthwhile show cave that has beautiful formations as well as other Moa remains found previously. I can definately recommend a visit if you are passing over the hill some time!

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