Back on the rocks
Posted: Saturday, 08 December 2007 |
Saturday the 8th Dec was the day for the second of the geology class field trips. Because of a combination of illness and really bad weather, there has been a bit of slippage in this department. However, we more than made up for it on Saturday! The forecast wasnt great, but there was a bit of a weather window, certainly for the morning. We met up at Carsaig pier at 10am and then set off to look at some rocks.
The road just above Carsaig was interesting as it was blocked by a fallen dead tree. Took 3 of us to clear it. This didnt augur well for the day (and more of this sort of thing later) however, it did stay relatively dry, even although it was soggy and boggy underfoot.
Everyone agreed at the end of the day, when the weather really came in that it had been well worth it and I think they all thoroughly enjoyed it. Moral of story: go for it. As Bill has put it to me several times " the weather always looks and feels worse from inside the house looking OUT the window!" Anyway, what did we see?
One of the other good things about this trip is that the timing meant that the tide was right out - this made for some seriously good rock exposure. I think this first time I have been to Carsaig when the tide was right out - well worth it!
Anyway, the crowd assembled:
We set off for the west side first of all - there is more to see here and we werent sure how long it would remain dry. Much of the beach is made up from shaly rocks with a lot of fossils in them. Carsaig is probably one of the best places in Mull to find fossils in fact. The fossil bearing shales are absolutely criss crossed by dykes and sills:
This sill is a good text book example of this sort of thing. It cuts across the shales and has hardened them in places. In this next pic, we have the sill on top of shales, and another thin sill underneath:
In thi snext pic you can see a dyke running straight towards the sill. Things get really complicated next, so we'll not worry too much about the details:
Right at the end of the sill, next to the sea there is a really strange looking thing - I reckon it is a xenolith, a piece of rock caught up in the sill as it was emplaced. The sills in this area are full of xenoliths, some of which have been found to contain sapphire. This one looks a bit like a canoe:
We continued to explore right to the waters edge:
There are a couple of small dykes which intersect - looks like a saltire:
Guess what, yet another dyke:
It has to be said, that if anyone wants to get a look at a lot of geology in a small area, it is hard to beat Carsaig - there is simply so much going on. And the interaction of igneous and sedimentary geology is everywhere. I personally reckon it is the best geological location in Mull which is easily accesible. There are arguably other more interesting places, but Carsaig is effortless as well as dramatic
Also, the rocks on the shore are Mesozoic - middle age rocks if you like. The basalts in the cliffs above are Tertiary - youngsters, relatively speaking. So between the two is the famous K/T boundary (Cretaceous / Tertiary - yes I know Cretaceous is spelt with a C not K but that's geology for you..) And what is special about the K/T boundary? Well it marks a major extinction in the evolutionary timescale - thats when the dinosaurs died out. Asteroid impact? Global warming? Who knows. We didnt find any dinosaur tracks, but hey, in similar rocks in Staffin in Skye, they found tracks not so long ago. It's actually about the only thing missing in Mull.
Sandstone in the clifff, showing big round "concretions":
I was here with the wee ones a few weeks ago, so full marks if you recognise that pic....
The walk back to the pier for lunch:
It was beginning to get a bit windy and starting to get wet, so we only had a short trip to the east side of the pier. I had been here on several other trips, and there are lots of pictures on some of my earlier blogs, so I didnt take many.
However, the cave behind the waterfall is always a neat place for a pic:
(By the way, I mentioned the fallen log earlier. While walking along the path to the waterfall, we noticed some seriously damaged trees - it appears that some large boulders had come crashing down from above. It must have happened very recently. Just a warning in case you are ever along that way!)
Neil in the pic is actually nice and dry as he is standing behind it!
And that was that. Back to the pier then back up the road in howling wind and lashing rain. But well worth it - an excellent morning well spent. Carpe diem!
We'll be back on the rocks again soon. Next weeks trip will be either a road excursion taking in lots of "roadside geology" or else, if the weather forecast is good, we will probably go to Ardtun and Fionnphort.
Cheers!
JW (MM)
The road just above Carsaig was interesting as it was blocked by a fallen dead tree. Took 3 of us to clear it. This didnt augur well for the day (and more of this sort of thing later) however, it did stay relatively dry, even although it was soggy and boggy underfoot.
Everyone agreed at the end of the day, when the weather really came in that it had been well worth it and I think they all thoroughly enjoyed it. Moral of story: go for it. As Bill has put it to me several times " the weather always looks and feels worse from inside the house looking OUT the window!" Anyway, what did we see?
One of the other good things about this trip is that the timing meant that the tide was right out - this made for some seriously good rock exposure. I think this first time I have been to Carsaig when the tide was right out - well worth it!
Anyway, the crowd assembled:
We set off for the west side first of all - there is more to see here and we werent sure how long it would remain dry. Much of the beach is made up from shaly rocks with a lot of fossils in them. Carsaig is probably one of the best places in Mull to find fossils in fact. The fossil bearing shales are absolutely criss crossed by dykes and sills:
This sill is a good text book example of this sort of thing. It cuts across the shales and has hardened them in places. In this next pic, we have the sill on top of shales, and another thin sill underneath:
In thi snext pic you can see a dyke running straight towards the sill. Things get really complicated next, so we'll not worry too much about the details:
Right at the end of the sill, next to the sea there is a really strange looking thing - I reckon it is a xenolith, a piece of rock caught up in the sill as it was emplaced. The sills in this area are full of xenoliths, some of which have been found to contain sapphire. This one looks a bit like a canoe:
We continued to explore right to the waters edge:
There are a couple of small dykes which intersect - looks like a saltire:
Guess what, yet another dyke:
It has to be said, that if anyone wants to get a look at a lot of geology in a small area, it is hard to beat Carsaig - there is simply so much going on. And the interaction of igneous and sedimentary geology is everywhere. I personally reckon it is the best geological location in Mull which is easily accesible. There are arguably other more interesting places, but Carsaig is effortless as well as dramatic
Also, the rocks on the shore are Mesozoic - middle age rocks if you like. The basalts in the cliffs above are Tertiary - youngsters, relatively speaking. So between the two is the famous K/T boundary (Cretaceous / Tertiary - yes I know Cretaceous is spelt with a C not K but that's geology for you..) And what is special about the K/T boundary? Well it marks a major extinction in the evolutionary timescale - thats when the dinosaurs died out. Asteroid impact? Global warming? Who knows. We didnt find any dinosaur tracks, but hey, in similar rocks in Staffin in Skye, they found tracks not so long ago. It's actually about the only thing missing in Mull.
Sandstone in the clifff, showing big round "concretions":
I was here with the wee ones a few weeks ago, so full marks if you recognise that pic....
The walk back to the pier for lunch:
It was beginning to get a bit windy and starting to get wet, so we only had a short trip to the east side of the pier. I had been here on several other trips, and there are lots of pictures on some of my earlier blogs, so I didnt take many.
However, the cave behind the waterfall is always a neat place for a pic:
(By the way, I mentioned the fallen log earlier. While walking along the path to the waterfall, we noticed some seriously damaged trees - it appears that some large boulders had come crashing down from above. It must have happened very recently. Just a warning in case you are ever along that way!)
Neil in the pic is actually nice and dry as he is standing behind it!
And that was that. Back to the pier then back up the road in howling wind and lashing rain. But well worth it - an excellent morning well spent. Carpe diem!
We'll be back on the rocks again soon. Next weeks trip will be either a road excursion taking in lots of "roadside geology" or else, if the weather forecast is good, we will probably go to Ardtun and Fionnphort.
Cheers!
JW (MM)
Comments
Brilliant blog MM! Talk about 'Britain's hardy sons' (and daughters) as Para Handy would have it, if some of these aren't Ramblers, I'm a Nederlander katte. Does the pressure of the hard stuff bearing down on it stop the shaley stuff from wearing away?
Flying Cat from Beware Falling Bould...SPLAT!
Brilliant photos as usual, MM, they show the geological features so clearly. I see your group includes a four-legged member, presumably he will be excused the test at the end ...
Jill from EK
Wonderful blogg, wonderful Mull! Please send me your e-mail address as I would like to contact you re. a geology tour when(if) I bring a bunch of 麓Swedes (not neaps) over next summer. Anne at IBHQ has it - a sk her for "Barney" of course.
Barney from Swithiod stable since the Cambrian
Hi MM - fascinating stuff - just wish I could join you but not possible at the moment - keep up the excellent work!
Wild Freckle from Mull
Anne has been transmoggified into Carol nowadays...just mentioning it...no, no need to thank me Carol@IBHQ...
Flying Cat from corrections and moggifications
Barney - no problem - I'll get a hold of IBHQ. Flying Cat, re the shale - what happens is that the shale actually gets hardened by the sill being intruded into it - so it makes it more resistant to weathering. At that sill in the picture, this effect was really obvious - classic textbook stuff. Other thing of course is that the edges of the sill cool a bit quicker than the main body so you get whats called a "chilled margin". Plenty of this to see at Carsaig as well. Carsaig is a magic place - I never tire of it.
Mountainman from Mull
Very cleaver MM, to take a pic of the group before any get lost. That way you will have a recent picture to give the searchers.
CVBruce from CA, USA
This takes me back to our Geography field trips at school. I loved them, even writing up the reports.
Carol from IBHQ
I feel I may be suffering from a chilled margin myself this chilly dank evening...Thank you MM. It is the mark of a true enthusiast and a gentleman, that he will answer the queries of a mere mog.
Flying Cat from on a warm thigh
Rocks, rocks, more rocks and, aye, a waterfall. Nice pics and a cheery, apparently well prepared bunch by the looks of it. But, let's cut to the quick and get to the important stuff though, Mountain Man. What did you all have for lunch? and what liquid help did you have to warm the gills?
mjc from NM,USA
mjc, I think the lunches were fairly inocuous. I dont remember seeing any amber liquid being passed around. Which is definitely not the way we did it when I was a student.....
mountainman from Mull
Thanks, FC, did I read in another of your comments (can't relocate it) that Carol was "spanking"? Would it be impolite to ask who... the mind boggles. (This is also a secret test of C.'s censorial tendencies).
Barney from Swithiod no hanky-panky
Now, behave. Remember, if you're not good, Santa won't visit.
Carol from IBHQ
Barney, spanking? No not me... dont think so anyway. You know just to check, I thought I'd do a google search on the words "91热爆" "island blogging" and "spanking" in the same search. Dont. You'll catch something.... try a search for "mull sapphire" or "cone sheets" or "porphyritic microgranodiorite" Much, much , much safer.... MM :-)))
MM from Tob
Carol I don't believe in SC (any relation to FC??) but I could be open to correction. MM, too many terms and you might miss out on the true lode. Once again, great blogg, great pix. Happy Chissy to one and all .. even TWS .. if we don't meet again in cyberspace until the New Year.
Barney from Sithiod and spankingly safe
Exploring the hills and coasts of Mull and Iona and occasionally elsewhere, with a close eye on the geology
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