Many of our students enjoy a semester or year abroad during their college time. Andrew Wayrynen ’17 is right now in New Zealand, one of the favorite destinations of Wooster geologists. He has generously shared some of his recent geological images with this blog. The striking section above is part of the “Pancake Rocks“, which are exposed on the west coast of the South Island of New Zealand near the village of Punakaiki. This is an Oligocene limestone that has been diagenetically altered by compaction and eroded into steep-sided shapes by freshwater dissolution and marine influence.
What looks like bedding in the Punakaiki Limestone is actually the effect of dissolution of the carbonate caused by immense overburden. One of our favorite Wooster geologists, structural guru George Davis, has a recent paper on this process (Davis, G.H. 2014. Quasi-flexural folding of pseudo-bedding. Geological Society of America Bulletin 126: 680-701.)
Andrew also visited the Moeraki Boulders on the Otago coast of the South Island. These are large spherical concretions weathered out of a Paleocene mudstone known as the Moeraki Formation.
These are septarian concretions, a type characterized by a three-dimensional network of mineral-filled cracks, as shown in Andrew’s image above.
Like the liberally-educated geologist he is, Andrew did not neglect to show the marine organisms encrusting some of the intertidal boulders. These, of course, are barnacles.