Mull Day 4 by Cat

Day 4

The Plateau Lavas

These make up almost all of Mull and are responsible for the amazing trap/step topography. We floundered across a lot of bog to reach Ardtun.  Stumbling down a steep and slimy gully (knowing our lecturer was filming putting more pressure on us NOT to fall)  we reached to famous leaf beds and the base of the plateau flows. At the coast this lowest flow showed spectacular columnar jointing (https://www.youtube.com/watch?v=Iek4OcrT6m0 appropriate accompanying music). Sadly didn’t get to see Fingals Cave or the fossil tree.

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A few road side stops allowed us to see how the closer we got to the igneous centres the greater the increase in hydrothermal alteration could be seen in the balsaltic flows.  Progressive contact metamorphism with veins of chlorite and epidote.

The last stop took us to see Igneous Centre 1. In a wee quarry below Ben Buie we examined the Ben Buie gabbro. Within the intrusion there were patches of pigmetites with large 5cm crystals. The intrusion has also been cut by one of the many cone sheets associated with the igneous complexes. These all dip in towards the magma reservoir and therefore can be used to estimate to centre of the volcano.

 

 

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