A visit to a petrified forest

We’ve had an interesting month of seeing fossils in Namibia.  After our visit to the Mesosaurus fossil site near Keetmanshoop, we wended our way up north to the Khorixas area in Damaraland, where we paid a visit to the petrified forest – which isn’t actually a conventional forest at all (and definitely not a bunch of trees that are scared out of their wits!)  It is, in fact, crystallized trees dating back to the Permian era, about 280 million years ago, when the area of Gondwana was in the grip of the Great Gondwana Ice Age.

A small rock log

When the climate warmed up, it caused great glaciers and ice fields to melt, which resulted in severe flooding.  This, in turn, uprooted and broke many enormous trees and sent them on a journey far from their origins.  Completely buried in silt and sand, the trees were not exposed to their usual decomposition.  Over time, more and more sand covered them and the quartz present in the sediment above the trees dissolved, causing rich silica deposits to leech into the wood.  The acidity eventually dissolved the organic matter in the trees and replaced it with crystalline quartz.

Bark of a petrified tree

When Gondwana broke up and split, the upheaval pushed the ground up and further erosion took place over the centuries.  Eventually the trees were once again exposed in the dry desert conditions where they can now be seen as fossilized trunks.

Petrified log

The trees grew to heights of 40 meters and were members of the Cordiates family (Dadoxylon arberi Seward).  Their structures were like conifers and pine trees as we know them.

Bark of a petrified tree

It is fascinating to see fossilized trees – you can see the bark, the rings, as well as the knots!

A knot

We were shown around by a trained local guide who had a very good knowledge of the trees, as well as the unusual welwitchia mirabilis plants that also thrive in this arid environment.

Rings are clearly visible

Namibia has some interesting fossil sites – apart from the Mesosaurus that I have already mentioned, you can also see dinosaur footprints near Omaruru.

 

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