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16 October 2014

mountainman


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Near a famous cave

Well it was back to Iona again on Thursday. I usually travel down from Tobermory on the Glen More road, returning by Gribun on the coast road. The Gribun road isnt nearly so fast, but the scenery on a good day is superb.

And more to the point, there are some rather nice places along the way to go and look at rocks and stuff! A lot of the good things to see are actaully right beside the road or not too far from it.

Anyway, near to Gribun is Mackinnons Cave which I hadnt been to for a long time. The tide was actually too far in to go to the cave itself, but the rocks round that whole area are simpy fascinating, Huge soaring cliffs, jagged rocks, pounding seas and birds shreiking. Tremendous stuff.

I parked the car at Balmeanach and followed the well sign posted path. First thing of interest is in the cliffs up above - a "transgressive " sill can be seen cutting across the lavas, meandering like a snake:


Actually, its not too clear at this resolution - you'll have to take my word for it!

Down to the shore and the cliff scenery starts to take shape:



The walking is quite ruggged in places and also muddy in parts. Watch for the tide as well!

Looking back the way, the inclined rocks you can see are quartzites, or psammites to give them the more up to date term. These rocks are very distinctive here - metamorphosed sandstones, with a very regular dip of about 40 degs.

There is rather a fine waterfall near the cave:



The tide was too far in for getting into the cave itself, so that was as far as I went. The entrance to the cave can be seen, sort of in this pic:



A wild place!

Heading back the way,the psammites show very clearly their sedimentary origin. The various layers are very obvious:





The pen is about 5 inches long, just for scale.

A very distinct quartz vein cuts across the psammites:



Although a lot of the rock is psammite, there are huge boulders of the various sedimentary and igneous rocks that outcrop further up the cliffs. One of the great things about this area is that you get the "big three" - igneous, sedimentary and metamorphic rocks all occuring together, and showing tremendous variety as well. The sedimentary rocks are conglomerates, limestones, sandstones and stuff like that. Some of the boulders are huge.



That grey stuff in the foreground is a conglomerate - all from above! Some of it almost looks artificial, like concrete. A close up view shows the pebbles embedded in it:



Looking out to Inch Kenneth, we can see the psammites that make up the foreshore - the rocks have a very distinctive "jointing" pattern - looks like hexagons and triangles:



Close up:



Finally, just before heading back up the cliff path and then back to the car, I found this rather neat orchid:



See, I'm not all hard rock - got a softer side as well!
More rocks soon!
MM


Posted on mountainman at 22:32

Comments

Wonderful pics again, MM. Caves: I went to the Bone Caves near Ullapool last week (it nearly killed me, I wasn't fit enough) and there are some terrific springs near there which just appear miraculously out of the ground. Possibly they are rivers that vanished further upstream into the limestone. I've been reading the geology book so you can't blind me with science any more (well, yes you can actually), and your photos well illustrate many of the topics covered. BTW, I assume your son was not available and you had to use your pen instead for scale? :-)

Jill from EK


your snaps just get better and better and as usual the blog is good!

the weather girl from hot and windy


Jill, thats right - on my own, no props, no junior helpers. Of course the traditional scale indicator amongst geologists used to be a lens cap off a Pentax K1000. These new fangled, didgy cameras dont even have that - well mine doesnt. Actually, talking of cameras, to my horror, I noticed a grey spot on the viewfinder and it also appears in some of these pics, esp the close ups of the psammites. You can just see it, about 1/3 of the way from the right, and about 1/3 of the way down - a fuzzy grey spot. Apparently, this is caused by dust on the CCD element, the clever bit that actually records the image. Not uncommon apparently. I managed to dislodge it by banging the camera on the desk...... Actually, I have twice managed to get dead hard disks working again by hitting them on the desk..... Worth getting to know these sophisticated technology tricks!

mountainman from Tob


Your pictures are, as always great. I always feel like I get an education every time I read your blog. Thanks!

CVBruce from CA, USA


I say, mountainman, you weren't a plumber in a previous existance by any chance? Hitting things that don't work is their forte....but that's not to say they then DO work!

Flying Cat from banging on a can


I am impressed by your high-tech approach to problems, but I think you have to know what you're doing before you can use such methods. A lay person such as myself would have only a broken camera/defunct hard disk if I tried it (not that I would dare touch the hard disk in the first place).

Jill from EK


From one island to another having found some of mine in yours, the pictures are beautiful and interesting. Even more interesting the snippets of reference to technology in Mull with a mind to remoteness.

Janet from Another Island




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