Mull Day 3 by Cat

Day 3

Mesozoic sedimentary succession

In a few places in Mull the Triassic and Jurassic rocks are exposed. We drove along long, twistly roads to reach Gribun. Being very careful not to annoy the farmer we headed to the beach (well more a mass of rounded pebbles = perfect conditions for trips and falls). The base of the succession was more Moine but instead the Morar psammites intruded by some pretty cool dykes: olive-nephaline and lamprophyre. On top was a Triassic conglometares which gave way to a cyclclic deposition of playa lake sediments (marls, desiccation cracks, calcareous noddules and flash flood deposits).

 cross cutting lamprophyre
cross cutting lamprophyre

 

getting creative at hiding from rain so our lunch doesn't get wet 
getting creative at hiding from rain so our lunch doesn’t get wet

In order to see the Jurassic we had a pretty steep climb into a gorge with hairy river crossings (which of course our group leader made look easy and leaves me questioning my fitness). We examined the evidence for marine transgression: interbedded shales, glauconitic sast and what remains of a cretaceous chalk deposit. On top of this was a thin, fine grained bed likely to be volcanic tuff which signalled the beginning of the Plateau lavas.

View up to the plateau lavas
View up to the plateau lavas

 

 

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