Edition #5 of the thriving geoscience blog carnival Accretionary Wedge at Green Gabbro has the theme Geological Misconceptions and Pie and features some excellent volcano-relevant posts:

Magma Cum Laude: Hot, gooey fillings
‘My least favorite geological misconception would have to be one that I come across a lot as an aspiring volcanologist: The Earth’s mantle is a molten sea of liquid, and the crust “floats” on it.’ It isn’t, and it doesn’t, and this post explains why that’s wrong and what actually happens superbly well.

Olelog: Mantle flow at subduction zones
‘Looking at cartoons of subduction zones you would think that the subducting slab would drag mantle material with it downwards and attract mantle material to the subduction zone from both sides in a more or less circular unidirectional flow on both sides of the subducted slab.’ It’s more complicated than that, and you have to think in three dimensions to see it.

goodSchist.com: Geological misconceptions – ooey gooey lava
‘You’ve seen lava flowing out of the ground, flowing from volcanoes, flowing here there and everywhere. So as someone who’s not studied the finer inner workings of the science of geology, you’ve likely extrapolated your observations and concluded that the mantle is liquid too. Well, you’d be wrong there. The mantle is solid, but has the unique ability to flow in the solid state.’ No-one is going to sink slowly into the free-flowing lava of the mantle, to the disappointment of movie-goers everywhere.

I’ve picked these three out because of their direct relevance to the things going on in the Earth that produce volcanoes, but all the posts in Accretionary Wedge’s carnival of good geological things are well worth reading. Explore and enjoy.