Hard Rock and Heavy Metal in Glenravel

Important mineral deposits have been found in the area

50 million years ago, Glenravel was the centre of considerable volcanic activity.  Molten lava bubbled and flowed out of huge craters and cracks to cover much of the country.

This activity was not continuous as after each eruption the lava flow cooled to form a vast horizontal sheet of basaltic rock, from 1m to 35m thick. The effects of a hot dry climate caused the new rock surface to weather and break down.

This formed a surface layer of clay and red coloured iron minerals. Alternate flows of lava and quiet weathering periods followed. Hundreds of these layers built up one on top of the other to a total depth of possibly 1800m. You can distinguish the top of each flow today by a reddish purple band in the rock.

One of these quiet, weathering periods was considerably longer than any of the others. The iron and clay minerals had time to form into a primitive soil. This caused some of the components to separate out into aluminium ore (bauxite) and iron oxide. In some areas the ore is so rich that it contains small pellets of almost pure iron!

This layer is known as the Interbasaltic Bed. Today's landscape is the result of erosion of the overlying basalt layers by ice and water. The Interbasaltic Bed can be seen in cliff faces, as at the Giant’s Causeway and in valley sides, as in Glenravel.

Look out for the line of mine spoil heaps and opencast workings where the distinctive red, 2-8m high, Interbasaltic Bed is exposed today.
Supported by the EU Programme for Peace and Reconciliation

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