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Tuesday, 24 February 2015

Igneous dyke, La Gomera


For the geologists in our midst.  One of the most amazing images of a dyke you are ever likely to see.  This one is exposed in a road cutting on La Gomera, high up on the "cumbre" above Vallehermoso.  The dyke has been intruded into red layered volcanic ashes and as it has melted its way  towards the surface (which must have been much higher than the eroded surface we see today) it has simply gobbled up the ash layers, leaving an incredibly clean contact on either side.

The dyke is made of basalt (I think) and it is about 10m wide.  The stone wall marks the edge of the roadway.  Because the road here is relatively new, this exposure is remarkably fresh.  Within a few years it will no doubt degrade.

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