This date in 1669 marked the official end of an eruption of Mount Etna which had started on 11 March, damaging several towns and villages. This eruption is considered the most significant of Etna’s historic eruptions. 10 things you might not know about Etna:

Volcanoes have always been regarded as places where spirits dwell, and reflecting on my own journey, I have visited a number of volcanoes in the Asia and Australian region. Also, I learnt about volcanoes during my time as an undergraduate taking one or two lectures on volcanology. Documentaries too (usually featuring Hawaii), had made up my previous intellectual diet on the topic of volcanoes.…

Driving about 30 miles west from my house up to 7,000 foot Darland Mountain, gives you views of Mt. Rainier, Mt. Hood, Mount St. Helens and Mount Adams. Not pictured but also visible: Mount Jefferson, Mount Stuart, Glacier Peak and the Goat Rocks.

I can see the TV from where I'm sat, and like. Dude. The guy says this is pretty closely based on a glacier he's actually seen. In Iceland no less.

Glaciers are dirty rivers of ice and rock. Some of them look nicer than others, and the more time marches onward, the less there are and the less that look photogenic, for obvious reasons. The other thing we have to look at is the geological setting.

Iceland, in general, is volcanic. What this means for glaciers is that they're forming over very hot material. Sometimes, this material rises to the surface. Now, magma does not always break the surface. One of the things that happens, especially in Iceland, is that glaciers topping volcanoes actually start to melt from the heat.

At this point, a few things can happen. The first and least interesting is that the heat cools off, magma solidifies in the conduit, and the melt re-freezes.

The second is that enough of the ice melts to cause a specific kind of flood. Those of you interested in MTG actually have seen the name for these floods on a card if you've dug around enough: jökulhlaup.

A jökulhlaup originally referred to floods specifically from the Vatnajökull icecap in Iceland, but has been adopted as a term for any sudden release of subglacial (underneath a glacier) or proglacial (formed by glacial damming. Think Ice Age 2: The Meltdown). Jökulhlaups can break out of a glacier with little to no warning, and cause lots of damage.

The third thing that can happen is a subglacial volcanic eruption. This may or may not break through the glacial cap, and will most likely be accompanied by jökulhlaups.

This kind of eruption has actually made strangely shaped mountains in places that were formerly glaciated in the Ice Ages. This kind of volcanic landform is called a Tuya. The etymology of the word is fairly ambiguous, per British Columbia Geographical Names, but might be from the Tahltan words for water (tu) and sky (ya).

In the case of an eruption breaking the ice cap, you will see what we got in the 2010 eruption of Eyjafjallajökull. This will scatter ash all over the glacier, which, allowing for good snowfalls, is eventually incorporated into the glacier. This will make the glacier even dirtier.