Ardalanish / Kilvickeon Geology trip
Posted: Sunday, 29 April 2007 |
I have put up some pics below to give you a feel for it:
Ardalanish Bay - nice folding in the Moine schists in this pic
After Ardalanish we had a quick little trip to Uisken for lunch and then headed off again, up to Scoor.
This rock seen in the pic above is a garnet amphibolite, near Uisken. Notice the size of the garnets (the ruler is one foot long) . This rock outcrops in several places between Ardalanish and Traigh Bhan na Sgurra, the beautiful bay below Scoor. The garnets although very large, are no good as gem stones as they are full of inclusions and quite impure. However, to find garnets of this size is unusual. Actually, some of the best examples are found as beach boulders - when eroded and polished by wave action, the garnets are really obvious in the rock. I'll try to find a pic for you!
Incidentally, my very first trip to Mull was as a geology undergraduate from St Andrews and we stayed at Scoor House - Nov 1979 it was.
There is a great little car parking area near the Kilvickeon church - anyone know how old that is? - from there it isnt far to the beach. And a great spot that is - beautiful, sunny, clean sand and no-one else about! We had a lot of fun investigating a sill intruded into the Moine metamorphic rocks - made more entertaining by the incoming tide so there was a bit of rock-hopping needed!
The beach at Kilvickeon - the island is connected by a sand bar - a feature called a tombolo. Most of the rocks in this pic are Moine schists and psammites (AKA quartzite) However, a sill has been intruded into the rocks on the left hand side of this pic - it isnt too obvious in the photo, but when down on the beach, the sill shows up as a very distinct brown rock in the grey schists.
The sill sof the Ross of Mull are famous for their xenoliths - xenoliths are large lumps of the surrounding "country" rock that get caught up in igneous intrusions. There is an absolute beauty at Kilvickeon:
Xenolith in the sill. Shaped a bit like the Isle of Wight! You can get a sense of the scale from the hammer (you can just see it - it has a blue handle and is about 12" long)
Here's another picture of the beach:
Looking westwards across Kilvickeon Beach
Final stop was the cliff above Port Bheathain - unfortunately we didnt have time to check it out properly as we had to be back in Salen at 6pm for the celebratory end of course dinner. The highest point here is a "dun" - Dun na Ceaird. A very fine vantage point witha great view of the beach below:
The beach below Dun na Ceaird, looking towards Port Bheathain. The coastline here is characterised by long promontaries and inlets with white sandy beaches.
Final picture is from the shore looking back towarsd the cliffs - note the almost vertical schists that are found here. The rocks are very shiny in places because of the large amounts of mica in them. When the sunlight catches them it can be quite impressive!
After this there was a bit of a sprint to Salen for dinner at Mediterranea!
Finally, just to say, this has been a very enjoyable experience - you were a great bunch of people to work with and I hope you all got as much out of it as I did. This is not the end of the story however - there will be more geological events over the summer - I shall keep you posted!
Thanks to everyone for taking part and I hope to see you all very soon!
JW (mountainman)
Comments
Oh wow, MM, these are just great, both the geology and scenic pics. The first one with the striations is just amazing, and the garnet one intriguing. I didn't know they occurred in that way. A question: how can you tell if a seemingly plain rock or pebble might contain a geode? I have several geodes (purchased) but have never found one in the wild (as it were) despite all my tapping and bashing.
Jill from EK
more lovely picture,thank you for sharing them
carol from france
Whatever you do, DON'T stop blogging - I need my geology fix!
Michelle Therese from Things Go Moo in the Night...
Next time Mr Trellis and I visit Mull, we'd like to take Mountainman round with us on our trips out. Two reasons - you'd be fantastic at pointing out interesting geological stuff, and also you seem to attract really fabulous weather, which, as we know, cannot always be guaranteed. Fantastic pics, MM, thank you.
Mrs Trellis from North Wales
Geodes eh Jill? Its actually hard to say - if it is a large one, and it is hollow, it will definitely feel "light" However smallish ones are more difficult. A lot of geodes , that are not broken, can look sort of greenish and "warty" on the outside. Agates are often like this - and it is only when you cut them open that the beauty is revealed. If you are interested in agates, best thing to do is a search for Scottish Agates on Google -the results will give you lots of good web sites that have been put up by various people - lots of really good pics. One of the experts on Scottish Agates was Prof Matthew Heddle - a fascinating character he was Professor of Chemistry at St Andrews in the late 19th century. Heddle amassed one of the biggest collections of Scottish minerals ever, and his agates were superb. Heddle wrote a book called "The Mineralogy of Scotland" - it is like gold dust now. There was a copy for sale recently at an online book seller who wanted $1000 for it (a 2 volume set) !! Most of Heddle's collection is in Edinburgh's Chamber St Museum - I actually worked on some of it one summer in 1977 when I was still a student. There is a very good minerals web site by Hal Currie: http://www.curriehj.freeserve.co.uk/ He has lots of descriptions of locations and what can be found. A great site, well worth a look! Hoep this lot helps you! Have fun! James
James (MM) from Tobermory
Thanks, James, I will follow this up and perhaps have better luck with my geode hunting. Maybe I should get a nice hammer like yours, too... The biggest geode I ever saw was in a minerals exhibition at Glasgow Uni some years ago. It was an amethyst geode about 5 feet by 4 by 3, and a small person could have climbed inside it. It was really something! but not the kind of thing you'd find on the local beach, I think.
Jill from EK
Very good pictures and interesting notes. Thank you # You would be happy visiting NM, traipsing around, methinks.
mjc from NM,USA
Jill, yes there are some seriously impressive geodes to be found. Another thing I find fascinating (and I keep going on about it to my students) is pegmatite. Pegmatite, for those that maybe havent come across the word is a very coarse variety of (usually) granite. The crystals can be several inches long in some cases. Great rocks for finding exotic minerals and semi precious stones. Pegmatites sometimes have geodes as well. There are stories of pegmatites which are so coarse, that quarries have been opened in a SINGLE crystal. Now this may be some sort of urban legend, but it certainly appears in a few text books. Places like the Cairngorms are good for pegmatites, also Knoydart. I have a piece of Cairngorm pegmatite which is much more radioactive than the normal background rate, due to the presence of minerals of uranium and thorium in it - not large quantities, mind you, certainly not dangerou
James (Mountainman) from Tobermory
I think, like Mrs Trellis above, that I will kidnap you and put you in my luggage (along with a bird expert and a botanist)next time I go anywhere at all. Someone with your knowledge could surely find interest in most landscapes, and could provide answers to all the things I wonder about. Pegmatites - I don't know these, will look them up. They sound rather unbelievable, especially the quarry-in-a-crystal ones - can this really be? And what would the stone from the quarry look like?
Jill from EK
Right, that last comment got chopped off at the "dangerous" bit. Pegmatites often contain strainge and unusual minerals and they frequently give a higher reading on a Geiger counter. I think the biggest minerals that have been a single quarry were beryl and feldspar. Beryl is actually found , along with large amounts of mica in the pegmatites of Knoydart. Mica was mined there during WW II as it was in short supply and needed for the war effort. There are good pictures of pegmatites from Knoydart on the SCRAN web site. www.scran.ac.uk This is an online resource of thousands of pics, videos etc - there are LOTS of geology pics in there. Well worth a look. However, you need a subscription to see the photos full size - if you have access to a School, College or University, you can get to it through your academic login. Otherwise you have to pay for a subscription - it isnt dear and well worth it! I would love to take a trip to Knoydart sometime soon - the hills are great and there is a tremendous sense of remoteness.
James (mountainman) from Tobermory
Thanks again, James. My only experience of Knoydart was a ride on the ferry from Mallaig to Inverie. Even without getting off the boat you could feel the remoteness and quiet - I believe it is only accessible by boat? We saw dolphins, too. The impresario Cameron Mackintosh has a house further up Loch Nevis, I believe. Lucky him!
Jill from EK
Thanks from the grandmother of a 7-yr-old "rock hound!" He thoroughly enjoyed the photos of sea and shore.
Barbara from Texas
Exploring the hills and coasts of Mull and Iona and occasionally elsewhere, with a close eye on the geology
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