Geological memories of our recent October 2014 holiday in Sicily. Did the earth move for you Toot?
Without my redoubtable partner to hold my hand and help me climb, I would not have made it to the top, thanks Toot!
Toot took this fantastic photograph of Etna through the window of the Easyjet plane, just after we left from Catania airport in Sicily, on our return journey to London Gatwick.
Etna is Europe's highest volcano and is one of the most active stratovolcanoes on the planet earth. For more information follow the link:
http://en.wikipedia.org/wiki/Mount_Etna
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| Etna - looking down from the rim of a cinder cone into an active fumarole. The main crater cones can be seen in the distance and at increased elevation. Ash and gas clouds are visible over the main active summit craters and the upper slopes are tinged yellow with sulphur. When the wind direction changed, sulphurous gas was blown our way and burned acid in our throats. |
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| Maps of Etna at various scales showing the location (yellow circle) in which the preceding photograph was taken and the lava samples were collected |
This rock was taken from the crater rim, just about where the people can be seen in the above photograph (the group on the right). Toot found it in a hollow which was actively gassing out. The yellow, presumably sulphur and the red presumably iron were probably the result of the gas depositing the minerals upon the cinder. The rock itself is of medium density, lighter than the sample we collected from a nearby lava flow but heavier than the pumice we subsequently collected from the beach on Stromboli. Close inspection with a magnifying eyepiece reveals small gas vesicles and a glassy crystalline crust of yellow, red and white minerals.
This predominantly red sample was collected close to the active fumarole you can see smoking in the photograph. Our guide told us that in August this vent had suddenly become active and consequently he had had to lead an emergency evacuation from the Volcano! So this rock is probably no more than 8 weeks old! It is about the same density as the other sample but much redder and with larger gas vesicles. Inspection with an eyepiece reveals one or two very small glassy mineral crystals.
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| Close up of the active fumarole. I felt quite nervous taking this photograph (Toot was a lot braver than me!) The sound affects are quite scary with rocks and ash constantly sliding away to oblivion, rattling and tinkling as they roll down the unstable ash slopes to be lost in the smoke and fire forever. |
For an excellent downloadable presentation, relating to Volcanoes and volcanic rocks generally and Etna and its lava particularly, follow the link:
http://web.pdx.edu/~jjackson/Etna.pdf
This image, looking towards the main summit craters, shows the lava field behind the active fumarole. We sat and ate our sandwiches here and watched as puffs of smoke issued sporadically from voids in and between the piled up and twisted lava boulders. Our lunch was taken at approximately 3000 metres above sea-level. The distant crater rims are about 300 metres higher and change with each successive major eruption or quake.
We laughed when we noticed that the low air pressure had caused our packets of crisps to inflate like balloons!
This sample of lava was taken from the lava field shown in the above photograph. In colour the lava is dark grey with a blue-green highlight. It has been contorted into a bewildering number of random shapes which have fused together to create an alien landscape. The lava is sharp and both dangerous and impossible to walk upon in safety.
The rock is much denser and has smaller and less frequent gas vesicles. Close inspection with an eyepiece reveals a number of small glassy white quartz like crystals.
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| Our view of the Summit Craters wreathed in smoke at 10.30 am. on the13th October 2014 |
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| Smoke from the fumarole blocks the sunlight as tourists march along the crater rim. |
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| Etna: major eruption (2001?) as seen from the International Space Station credit Reid Wiseman/NASA |
Credits: Wikipedia, NASA, The Earth Institute Columbia University, Portland University and Easyjet
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