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18th May: Friday morning and it was a case of "Where shall we go?" The weather wasn't great but we needed a trip somewhere - the coast along Loch na Keal and Gribun can be quite interesting in bad weather - and the rocks are neat as well, so off we went. Actually, the weather was not too bad - windy rather than wet - white caps on the waves were plentiful. On the way towards Gribun, on the shore of Loch na Keal, I notice that the sun was really picking out some rocks on the opposite shore:



This pic is an enlargement of an image taken at the full telephoto setting of the camera - so it isnt great, but shows the columns well. Whether this is a sill or a lava flow needs more study. Quick update on Saturday: Having checked the maps and the Survey memoir, it appears that it is just a lava flow like so many others and not a sill. It looks similar to the columns in Ulva and may well be related.Need to get down to it some time and have a look!

On to Gribun - not a lot of good places there to park a car but just opposite Inch Kenneth there are a couple of places. We walked along the shore to a headland that sticks out towards Inch Kenneth.



The rocks in the foreground are a very hard limestone type of rock called cornstone - there is a lot of it in this area - there is also a lot of sandstone and conglomerate, all of Triassic age so this is a good place to see sedimentary rocks. There is a very distinct green sandstone found here. the next pic shows the junior geologist examining it closely (No he wasnt asked to stand there just to give a sense of scale...)



I noticed a very freshly brokern surface in this sandstone nearby. Probably some geologist hitting the rocks! One of the very distinctive things about this rock is the dessication cracks that cover it. See this pic:



and this one:



The cracks were caused by the rock drying out and then being infilled by soem other material. Judging by the colour, I would say that the infilling material was iron rich - it is certainly very different from the sandstone. It is also more resistant to weathering, so it stands up, proud of the surface.

The weather started to change and so it was back to the car with Iain.

Further back up the road, near Scarisdale Point, I stopped to have a look at something that relates to much more recent geological history. There are some very obvious grooves and channels cut in the shore rocks here. These are known as P forms, and represent the gouging effect of glaciers on the rock. Go to:

http://www.swisseduc.ch/glaciers/glossary/p-forms-en.html for a good explanation (and a picture from elsewhere in the Highlands)

Here are the Loch na Keal P Forms:





The whole are is cut by dykes as well, some of which are very interesting, but that can keep for another blog entry!

Actually, this whole coast is full of interesting stuff, it is also easily accesible and with the soaring cliffs behind you and great seascapes in front, you just cant go wrong!