As KarenZ correctly remembered my mate and me hiked Las Cañadas Caldera in Tenerife last september. We joined a group walking on Alexander von Humboldts steps. The famous scientist visited the island 1799 when he was on his way to South America. It is reported that his guides never led him to the very top of Teide against his wishes. But as long as there are quite some “Alexander von Humboldt” hike trails in the caldera and our walk led as away from Teide and not towards it, i seriously doubt i really actually walked in Humboldts footsteps.
I had been hoping to gain information about the geology features from the guide too, but even being a volcanic layman i think i knew more about it, than he did. After my first few questions he tried to avoid further questions about stones at all costs. (Starting to walk a lot faster or starting a conversation with someone else 😉 ) Naturally i had been reading up on what i might have to expect. Phonolite was among the stones i was expecting to come across. I had not been thinking about the names origin and was not sure if i could identify it. When we took a lunchbreak i kicked a stone and suddenly i heard a melodious “klink”. Oh what was that? Could the name phonolite come from phono meaning voice or sound. It does. And then the group saw me jumping around and knocking the rock you saw in the riddle (above) and neighbouring rocks with a tiny one. I had great fun and i think the rest of the group thought i was pretty crazy.
2 videos were found on youtube by Diana and Jamie. ( I like the second one better , besides the song quality, also because the stones i knocked on, sounded darker than the sounds in the first video.)
Here’s wikis take on the genesis of Phonolite: “Phonolite is unusual in that it forms from magma with a relatively low silica content, generated by low degrees of partial melting (less than 10%) of highly aluminous rocks of the lower crust such as tonalite, monzonite and metamorphic rocks. Melting of such rocks to a very low degree promotes the liberation of aluminium, potassium, sodium and calcium via melting of feldspar, with some involvement of mafic minerals. Because the rock is silica undersaturated, it is free of quartz or other silica crystals, and is dominated by low-silica feldspathoid minerals more than feldspar minerals.
A few geological processes and tectonic events can melt the necessary precursor rocks to form phonolite. These include intracontinental hotspot volcanism, such as may form above mantle plumes covered by thick continental crust. A-type granites and alkaline igneous provinces are usually found alongside phonolites. Phonolites may also be produced by low degree partial melting of underplates of granitic material in collisional orogenic belts.” (Thanks Wiki) ( And Thanks Diana!!!)
Obviously the Devils Tower National Monument is made of phonolitic porphyr too. Here is a paper on it: http://www.nature.nps.gov/views/Sites/DETO/HTML/ET_Igneous.htmand here is a beautiful image made by one of the TWAN photographers Wally Pacholka.
We all noticed that Iceland was really quiet lately but Jamie pointed to an article about Hekla´s inflation. Here is the Giggle translate version.
To me it appears that Giggle learned understanding Icelandic a little better since Ejyafjallas eruption, though one lines says, the volcano is ready for soda. So… Hekla is thristy… poor little volcano. (just kidding, of course)
There has been quite some talk about Campi Flegrei on the internet in the last weeks. Some links provided by users:
Video pointed out by ScienzaObsoleta as well as this link to the ground deformation. http://www.ov.ingv.it/ov/images/stories/rite-up-ultimo.png
Dr Boris B´s commented over at eruptions :http://www.wired.com/wiredscience/2013/01/the-restless-campi-flegrei-caldera-volcano/
In Italian: http://www.ov.ingv.it/ov/en/campi-flegrei.html
Thanks Alyson and Bruce.
Erik Klemetti on the Paluweh eruption today with NASA images of the ash plume:
On the earthquake Mag 8 ( or 7,9) which hit Santa Cruz. The Solomon Island saw a 1 meter high tsunami wave which destroyed 3 villages on the island Nendo. Till now 4 people were reported to have been killed. CNN says the tsunami warning for other countries was canceled.
Quite a lot of afterquakes: http://geofon.gfz-potsdam.de/eqinfo/list.php
The riddle Name that volcanoes was finally solve and completly blown by Alison. One point goes to tgmccoy. https://volcanocafe.wordpress.com/name-that-volcanoes-answers/