Day 2 – Monday 29th April 2019
WEGA in the North West Highlands Geopark
Our first stop was at Achmelvich where we were to look at the Lewisian. But what we looked at first was the wonderful beach. It looked its wonderful best – blue skies, blue sea, white sands. And the temperature was reasonable!
We were headed towards some Lewisian Gneiss with a cross-cutting Scourie Dyke. The gneiss is about 2,400Ma, the dyke “only” 2,000Ma.
The dyke textures remain unaltered but there is some minor shearing along the edges.
After observing (or being observed by) some Sea Eagles we walked over the headland to look at some more Lewisian.
We then moved on to Clachtoll where we came across a formation which was new to me – the Stoer Group. This is a rock very similar to Torridonian but which underlies it and is 200Ma older.
It lies unconformably on the Lewisian, with its lowest members being a basal breccia.
We went from the bottom of the Stoer to something a bit higher in the succession but passed a lovely Heilan Coo on the way.
What we were going to see was the earliest signs of life so far discovered in the British Isles! Admittedly the signs are not very spectacular but they are there!
They are the remains of cyanobacteria (which used to be known a blue-green algae) which enjoyed life as scum on a pond, occasionally sinking to the bottom and forming the structures we see below.
Our final stop for the day was on the coast, near Stoer village to look at the Stac Fada formation.
The latest interpretation for this formation is that it is an impactite – a rock formed from the debris of a meteorite impact. If you believe THIS REPORT the meteorite struck the earth near Lairg. And if you believe THIS REPORT it impacted in the Minch
We then headed back to Ullapool to prepare for our next excursion.
But we had a view of Suilven on our way back to the van.