On the trail of Shetland’s volcano

Allen Fraser (UK) For a land area of just 1,468km2, yet within a staggering 2,731km of coastline, Shetland has probably the most complex and diverse geology and geomorphology to be found anywhere in the World. Part of Shetland’s Geopark plan was a suggestion from the community of Northmavine that a geological gateway be established to their area at Mavis Grind, and a volcano trail be set up around the dramatically beautiful Eshaness. Fig. 1. Map of Eshaness. Although it is hard to imagine today, some 350Ma ago, the peninsula of Eshaness was a fire and lava-belching volcano. In fact, the name “Esha Ness” comes from the Old Norse language and means the “Headland of Volcanic Ashes”. The beaches and cliffs of Eshaness show many fine examples of the rocks that formed in this ancient volcano and tell us something of the environment in which the volcano grew. Fig. 2. The Eshaness peninsula. Setting the scene Eshaness’ story begins some 400Ma (in the Devonian period) when three of the Earth’s tectonic plates converged and eventually formed a huge continent now referred to as Pangaea. This collision threw up the Caledonian Mountain chain that was originally of Himalayan proportions but which rapidly began to erode. Rivers carried the erosion products (sediments) into lakes that formed in valleys between the mountains and on the plains below the foothills of the mountain chain. At this time ‘Britain’ lay in equatorial latitudes so the rocks we see exposed today were often laid down in environments … Read More

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