Better for Clouds and Geology than Snow Today.
8th January 2017
It was another mild day with various layers of cloud at different levels. I went round the Nid Ridge to G+T Gully which I found to be looking a bit sorry for itself snow wise. This is an area often used by groups to practise various winter skills. It is an area which has some interesting geology, and unless it is very snowy, there is usually enough rock visible to see something geology wise.
The majority on Aonach Mor is made of granite. This was pushed up as a dome of magma roughly 400 million years ago, but did not break the surface, and slowly cooled deep underground to produced the large grained granite.  As this magma was pushing up, minerals in the soft rocks surrounds in magma dome minerals with lower melting points started to get squeezed out of some layers, and get concentrated in others, while thin fingers of granite pushed into any weaknesses. This produces the patterns, contortions intrusions which can be  spotted and admired by avalanche forecasters (and others) around the base of G+T gully, especially when there is no snow. Later intrusions in the granite were preferentially eroded away to give parallel sided gullies of Coire an Lochan, such as Left Twin, which are appreciated by winter climbers.
Another area or interest geologically is the mountain bike track down from the top station. This is is right on the border of the granite. Therefore,  if you ever miss the gonolda after climbing, or it is winded off, then take it as an opportunity to appreciate the on the bike track, rather than just viewing it as an  inconvenient schlap up/down the hill.
This is a summary of my understanding of the geology of Aonach Mor, but if I have got anything wrong please feel free to point this out.
An impressive bank of cloud on Aonach Mor
G+T gully looking rather sorry for itself.
Some interesting rock near the base of G=T gully!
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Louis
9th January 2017 10:31 am
Interesting detail on a rubbish day, appreciated, thanks.
lochaberadmin
11th January 2017 2:30 pm
Glad you found it interesting Louis.