28 October 2010
Spooky Deskcrop – Accretionary Wedge #28
Posted by Jessica Ball
The latest Accretionary Wedge is being hosted at Research at a Snail’s Pace by Matt Kuchta…and the theme is deskcrops (spooky if possible, for Halloween!) My favorite deskcrop is one that I acquired fairly recently on Montserrat, from the February 2010 dome collapse deposits of the Soufriere Hills volcano. This isn’t a particularly small sample, but it was one of the easiest to collect – already pre-rounded, and of course it didn’t add much mass to my luggage, because it’s a chunk of pumice! (Sorry for the color variations in the next few photos – I was using the cheap camera and the color balance always goes wonky on that one.)
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Femur figure courtesy of Gray’s Anatomy, via Wikimedia Commons. |
But don’t worry! That mark has nothing to do with human remains (no one was killed in that dome collapse, and I would never disturb remains if I came across them). It’s actually a scorch mark from a tree limb that I found the pumice block resting against. Remember this photo?
And, for all you mineralogists out there, here’s a really nifty little shattered hornblende phenocryst. (The predominant composition of the eruptive products at Soufriere Hills is andesitic, so there are also quite a few large plagioclase phenocrysts in there as well.)
Scorching!
One of my old field professors told stories of a basalt from one of the cascade basalt fields with a femur sticking out which they called “the slow Indian”.
Never saw the rock myself, though.