Basalt columns in the Hebrides.The Isle of Staffa is an island off the coast of Scotland. Formed ent

Basalt columns in the Hebrides.The Isle of Staffa is an island off the coast of Scotland. Formed entirely of volcanic rocks, it is one of the many remnants spread around the north Atlantic of the massive volcanism that accompanied the rifting of north America from Europe in the early Paleocene. The Giant’s Causeway in Ireland is another famous lava from the same series of eruptions. Basaltic lava flows overlie early erupted tuffs (welded ash deposits), and one of these layers cooled to form the classic columnar jointing that distinguishes volcanic rocks.The island was covered by thick ice sheets during the ice ages, and is now slowly rising out of the sea due to isostatic rebound. As the weight of the ice is removed, the layer of the earth between the crust and mantle (called the asthenosphere) that had been pushed down bounces back up due to buoyancy, pushing the overlying crust up with it.Fingal’s cave is also on the isle (previously covered by TES at http://tinyurl.com/lths8bu), and the sound of waves crashing within is said to have inspired Mendelssohn’s Hebridean Overture. LozImage credit: Otter Films/Maramediahttp://www.geotimes.org/oct06/Travels1006.htmlhttp://www.bbc.co.uk/programmes/p014g3q2 -- source link

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