In the Company of Volcanoes

- Dr. Alison Graettinger “If there is one thing I’ve learned, it’s never to stick your hand into a viscous material” I came across that quote again in the signature of a colleague's email. It is from the 2004 Van Helsing movie. The movie is a bit cheesey, but that advice is very sound. So what does viscous mean? The term viscosity is not a word that most people use every day, but a really useful one if you want to know anything about a fluid or anything that flows. It gets used by your mechanic when discussing different types of oils to put in a car’s engine. Or occasionally in movies involving evil scientists, monsters and gooey things (see above). Even TSA has to have a basic understanding of viscous things as they limit all things that pour, spreads or smears. This covers a range of things that, while they behave like fluids (which means they deform under a force), you might not immediately think of them. Unfortunately, TSA is as just as likely to take away your hair gel...

- Janine What happens when you get really viscous rhyolite (high silica content which makes it very sticky) magma rising to the surface? Well, it either stops, produces a really big bang, or oozes. When it stops below the surface it forms granite , which we see a lot of nearby in Yosemite . A build up of gasses that produces very high pressures can result in an explosive eruption, like certain eruptions that have occurred in the past at Yellowstone and Long Valley calderas. When the conditions aren't right for an explosive eruption, a more quiet 'oozing' of lava occurs at the surface that creates some really fantastic looking rocks! If you want to see a great example of rocks where you can see how they moved, head over to the Inyo domes volcanic chain near Mammoth mountain in California. The Inyo domes are near the edge of the Long Valley caldera , Yellowstone's less infamous cousin, west of the Mono domes chain. The Inyo chain is a group of rhyolitic domes and fl...