CHRISTCHURCH, NEW ZEALAND–Andrew Collins, our Wooster Geology student abroad in New Zealand, has posted another set of photographs from his adventures. Of course they include field geology! Here is one of his images from a recent outing:
Cave Rock near Sumner, which is a suburb of Christchurch, New Zealand. Photograph by Andrew Collins.
This view fits into one of our major themes this year: basalt! We had plenty of it on the Mojave field trip, the Utah group dabbled in it, and the Iceland team is defined by this dense black rock. Now I’m no expert, but here’s my interpretation of the above outcrop: it looks like a basalt flow over a coarse conglomerate with a magnificent baked zone at the top of the conglomerate (the bright red) and a chilled zone at the base of the basalt. What do you think?
I think it looks pretty sweet, graffiti and all. Why is it such a bright red?
I’m hoping it’s not paint!
Lava flows are often separated by flow-top breccias that contain cinder and are oxidized, giving them the bright red color. Also, if soils developed between eruptive events, the baked soil horizon can be highly colored – red, yellow. Just beautiful, really.
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