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!
Jessica Ball is a volcanologist at the U.S. Geological Survey, researching volcanic hydrothermal systems and stability, and doing science communication for the California Volcano Observatory. She previously worked at the Geological Society of America's Washington DC Policy Office, learning about the intersection of Earth science and legislative affairs. Her Mendenhall postdoc and PhD focused on how water affects the stability of volcanoes, and involved both field investigations and numerical modeling applications. Her blogging covers a range of topics, from her experiences in academic geosciences to science outreach and communication to her field and lab work in volcanology. 
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.