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On Saturday, 25th we (my geology students and a few others) planned to walk, at least part of the world famous Loch Ba Ring Dyke. At the time of its discovery, this was called the "most perfect example of a ring dyke known to science" and it represents one of the very last examples of igneous activity in Mull, if not the UK.

So its kinda special. And we had decided that walking the whole length of it was a good idea. Well, yes it is, if the weather is good. Saturday morning was wet. Very wet. The ground was saturated, the streams were seriously full and we all got soaked. But who cares? We had fun. Lots of it.

So for any of you who think I only go out on good days, this was different. Very different...

If you want some info on the Loch Ba Ring Dyke, my own geology pages have a whole section on the walk at: www.mullgeology.com/LBRD_walk.html Also there is a good section on the scottish geology portal site:

http://www.scottishgeology.com/outandabout/classic_sites/locations/mull_loch_ba_ring_dykes.html

Anyway, what did we see?

Th LBRD runs from Loch Ba up on to Beinn a Ghraig down to Glen Clachaig, round Beinn Chaisgidle, over to Glen Forsa and then back over to Loch Ba. It is about 15 miles in length. The most obvious part of it is the section running up to Beinn a' Ghraig, where it appears as a definite feature against the skyline. Ring dykes are also found in Ardnamurchan as well as Glencoe.Although the LBRD is one of the last igneous events in Mull, it is actually traversed by some later dykes. One of these has weathered out to give this chasm:



Here we have a classic example of a dyke that has eroded away to leave a steep sided gorge. The river that runs through it was absolutely charging through! Here is a picture taken a few weeks ago to show it when it was dry:



There is an interesting aspect to all of this. The word "dyke". In Scots English, it means a wall. In English English, it is a ditch. Since a geological dyke (or dike if you are American) can look like either a ditch or a wall, then the word is most apt. Incidentally, the Gaelic word for ditch is "d矛g" pronounced jeek (with a long ee sound) which is much more like the English usage than the Scots.....

We walked up a bit onto the dyke itself - the rock is fascinating, being a mixture of basic and acidic igneous material. In this picture you can see swirls of basic material (basalt) in the main rock type which is acidic - called a felsite. This combination of both types is actually a highly unusual type of rock.



However, the weather was pretty grim so we decided that it would be best to head over and down and call it a day. A quick lunch stop took place beside a lochan - look at the mist:



Wet but quite happy (I think)! As always, if there are toadstools to be snapped, I'll take its pic:


That one was about 2" across.

From this point, just south east of the dyke, we needed to head down to the estate road. It got rather interesting at this point. There are several small streams to cross. Normally, these are a doddle. Not today. Because off all the heavy rain, they were seriously swollen and were actually a very good illustration of the dangers that can exist in the hills at any time of year (its supposed to be summer in mid August...) However with a bit of care we got down OK

And then it was back to the cars at the end of the road. Great fun, but the complete Ring Dyke walk will have to wait for a better day! And then there was the social evening later - many thanks to all who attended and a huge thanks to Alison and Vic for letting their house be taken over for several hours. A great evening and hopefully I'll see you all when the classes start again in a few weeks time!

Just to finish with, here are a couple of pics of what it SHOULD look like up on the dyke: (Note these were taken some time ago)


Up high , the dyke just looks like a wall of rock at the back of Beinn a' Ghraig


And this pic is the view back down the dyke towards Loch Ba