Visit to Torr na h-Annaid ROMG Contact

The final location I visited a part of my short trip to the Ross of Mull was to Torr na h-Anaid next to Bendoran Cottage near Bunessan. This is another classic locality where sillimanite is found in the metamorphosed Moine rocks close to the contact with the granite. In the Zaniewski paper I mentioned previously there are some interesting features to be seen at this location. It doesnt take long to visit as it close to the road. Last time I was on this actual site was in November 1979 as an undergraduate!

Heres the view from the road (Google Streetview as I didnt take a pic of the hill:

View from the road up to the hill

Torr na h-Annaid is famous for the development of sillimanite near the contact. After searching about for a bit, I found some rock surfaces where it clearly forms "knots"

Sillimanite knots in the Moine schist - ruler for scale

There was also a small vein of pegmatite nearby:

 Vein of pegmatite cutting the schist

And a close up of the same - Quartz, K Feldspar and Muscovite clearly visible

According to the paper, anatexis of the crust has taken place resulting in a migmatite being formed. This shows up well on the side of the crag facing the cottage

Migmatite is the whitish material veining the schist

Another view showing xenoliths of Moine schist in the migmatite

After that short visit it was back to the car and then back to Tobermory. An excellent end to a great few days looking at the Ross of Mull Granite. Lots of ideas for this years geology walks as well.


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