EGU Blogs

Geology Photo of the Week #9 – Oct 21-27

Check out this wicked awesome rock!!

This awesome formation is aptly known as “Split Apple Rock”. It is probably one of the more unique rock formations that I have seen. It is located in Abel Tasman National Park in New Zealand’s South Island. As the with the Pancake Rocks post a few weeks ago I was in the area for a conference and was touring around afterwards. Split Apple Rock is composed of granite.

The theory on its formation is an interesting one. From what I have been able to discover online, which is very limited,  the consensus is that this formation had a glacial origin and that it formed due to freeze-thaw fracturing, although I am not sure that this fully explains it. I realize that this area was glaciated, however, I would think erosion by sea spray on an already existing fracture could make something like this too. If you know more about this rock please comment or simply state your opinion!! Meanwhile, enjoy the pictures.



Matt Herod is a Ph.D Candidate in the Department of Earth Sciences at the University of Ottawa in Ontario, Canada. His research focuses on the geochemistry of iodine and the radioactive isotope iodine-129. His work involves characterizing the cycle and sources of 129I in the Canadian Arctic and applying this to long term radioactive waste disposal and the effect of Fukushima fallout. His project includes field work and lab work at the André E. Lalonde 3MV AMS Laboratory. Matt blogs about any topic in geology that interests him, and attempts to make these topics understandable to everyone. Tweets as @GeoHerod.


  1. Nice rock! I believe that some sort of structural or compositional weakness had to be there before splitting. I wonder if strong lightning bolt could also help to split it.

    • I definitely agree. Whether it is from freeze-thaw or from sea-spray erosion some sort of fracture had to exist already. The round shape of the rock itself is what makes me think it is erosive since I can’t see such a shape resulting from glacial abrasion/sub-glacial water erosion…especially for a boulder. Your lightning bolt idea is interesting. I never considered that. I wonder if there would be a way to test it out? Thanks for your comment!

  2. I see boulders split like that when I drive across the Sierra Nevada mountains in California, USA. The only mechanism there is freeze-thaw. (Spalting happens, too, but doesn’t split boulders that way.) However, the Sierra Nevada boulders are quite rough-faced. Freeze-thaw could certainly have split your boulder, but it’s been rounded and softened by sea spray since then.

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