One of my favourite types of stones to find at Gemstone Beach in Southland is the argillite that has trace fossils in it (see photos above). There are a few variations of them, with different coloured stones (green, red, black…) and different trace shapes (the most attractive to me being the lines of chevrons). There are lots of these stones there, and I have found them too at Riverton Aparima. See, for example, “Southern Sojourn 2023(18): The Tattooed Rock, The Trace Fossils… Revisiting Gemstone Beach’s Trace Fossil Stones, February 2023” and “U is for Unusual Variations of Trace Fossil Stones and V is for The Chevron Shape of Trace Fossils”.
I have become aware that trace fossils in argillite can also be found elsewhere in New Zealand. After I moved to Whanganui a few years ago, I was told that on rare occasions they could be found on nearby Castlecliff Beach, then my wife found a couple on South Beach when riding her horse there. Bruce Taylor, a keen fossil hunter, showed me a couple he had found on Kai Iwi Beach. These have all been green stones, the most common colour down south too. I have been keen to find one for myself. For a few weeks, I have been walking our dog early in the mornings on Kai Iwi Beach:
During our walks, I constantly scan for stones to tumble polish. There are very few stones there, usually widely-scattered, and not many are colourful or interesting. Mainly iron-stained quartz can be found, which often tumble polish well – see “The Iron-Stained Stones of Kai-Iwi Beach” and “K is for Kai Iwi Beach Stone” . I always hope to come across an argillite with trace fossils but for a number of years, my hunt has been fruitless, without even a green argillite being spotted. Then last week I finally found a small green argillite with a trace fossil!
It’s quite small and innocuous. The main trace fossils in it, probably burrows, are rather plain. There are hints of maybe other smaller traces, difficult to see. But to me, this is an outstanding find, long awaited.
The waves have rearranged quite a bit of sand on Kai Iwi Beach recently, mostly removing it along one particular stretch of a couple of hundred metres. As a result, there seems to have been an increase in the scattering of stones that appears along the wave’s edge. That’s where I found this small trace fossil stone, more than 500 metres north of Archer’s Bridge, the pedestrian bridge over the Kai Iwi Stream.
Whenever I am on any beach, I can’t help but scan for stones. For the next few weeks, I will be on Kai Iwi Beach each morning, walking the dog so, who knows, another one might turn up. Or not.
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