![\"Volcanoes](\"http:\/\/all-geo.org\/volcan01010\/wp-content\/uploads\/2013\/09\/Volcanoes-of-Southern-Iceland.jpg\")
<\/a>Volcanoes of Southern Iceland, as seen from Hella. Fresh September snow highlights the higher volcanic peaks.\u00a0 Click to enlarge.<\/p><\/div>\n
The image lists the dates of “historic eruptions”.\u00a0 For Iceland, this is since the country was settled in 871+\/-2 A.D.\u00a0 The dates are taken from the catalogue of the Global Volcanism Program<\/a>.\u00a0 The 870 A.D. eruption of Torfaj\u00f6kull produced pale-coloured rhyolite magma and coincided with the eruption of dark-coloured basaltic magma from the Vei\u00f0iv\u00f6tn fissure further northeast.\u00a0 The combination of eruptions produced distinctive two-coloured tephra<\/a> (pumice and ash) marker layer that can be found in soil across the country called the Settlement Layer or Landn\u00e1m tephra<\/a>.\u00a0 It can be used to look for environmental changes since people (and their sheeps) arrived in Iceland.<\/p>\n Only Hekla looks like the classic cone-shaped volcano that a child might draw (and even then it is only from this angle, it is actually a SW-NE running ridge).\u00a0 The other volcanoes were mainly constructed by eruptions when Iceland was covered by ice over 1000 m thick.\u00a0 Instead of lava flows, they contain lots of broken rock fragments, shattered when the hot magma hit cold meltwater (called hyaloclastite<\/a>) and piled up where they erupted.\u00a0 Most of the Hekla cone has formed since the ice melted, around 8,000 years ago.\u00a0 Tindfjallaj\u00f6kull has had no historic eruptions, but it has some lavas that haven’t been affected by glaciers, so has had at least one eruption since then.<\/p>\n The image was stitched using Hugin<\/a>, a free\/open source<\/a> panorama stitching program, and annotated with Inkscape<\/a>, a free\/open source<\/a> Adobe Illustrator\/Corel Draw.\u00a0 They can be installed on Ubuntu-like Linux systems with the command sudo apt-get install inkscape hugin<\/em>, and is also available for Windows and Mac.\u00a0 My photos don’t really do the scene justice, so you should probably just go to Iceland and see for yourself.<\/p>\n","protected":false},"excerpt":{"rendered":" The panorama above shows the volcanoes of Southern Iceland highlighted by early Autumn snows.\u00a0 Click the image for a full size version.\u00a0 It was taken near the town of Hella.\u00a0 From left to right, they are Hekla, Torfaj\u00f6kull, Tindfjallaj\u00f6kull, Katla … Continue reading