Friday 3rd May, 2019

WEGA in the North West Highlands Geopark

Day 6 – Friday 3rd May 2019

Our day in Achiltibuie produced the worst weather we experienced. But that was only in the morning and it was only short but sharp squalls.

Were we downhearted? Not very much as we were looking at some rather interesting Lewisian which had garnets in it!

There is a very good leaflet on the geology of Coigach which you can download from HERE. We were fortunate to have its author, Dr. Patrick Cossey, with us, to show the outcrops.

Our route can be seen on the map below. A selection of the my photographs are used below. You can see all of them HERE.

In the morning we looked at the Lewisian North east of the vilage, after lunch we searched for the Stoer-Torridonian unconformity.

In this area the Lewisian is a dark-coloured, coarsely crystalline amphibolite with black hornblende  and red garnet . This rock once formed part of a layered sill which has been metamorphosed at high temperatures and pressures.

Lewisian Gneiss
View of the Summer Isles from the Lewisian
Lewisian Gneiss - Amphibolite block in tightly folded gneiss

The weather was not kind for photographers so I did not take many photos.

We walked back to the community centre where coffee and cake was very welcome.

Then out once more to look at the Stoer Group and the Torridonian. But first we found the Stoer on top of the Lewisian. the outcrop was unusual as most of the rock was Lewisian but they were boulders in a sparse matrix of red Stoer sand.

Blocks of lewisian in a Stoer matrix - the base of the Stoer Group.
Higher up in the Stoer

Eventually we found the Torridonian. It was very similar to the Stoer but had a different dip.

On the Torridonian, looking over the Stoer towards Ben More Coigach
Torridonian on Stoer
The unconformity between the Torridonian and the Stoer.

Then back to the van and back to Ullapool at the end of a fascinating week of geology in the North West Highlands Geopark!