UKC

Or even gifted amateurs in that field.

Help me settle an argument before it starts.

Which of these options best describes the Dubh Loch which sits below Creag an Dubh Loch and its formation:

A. A corrie lochan (or tarn if you prefer) sitting in a corrie and so produced by the kind of corrie forming processes you learn at Standard Grade / National / GCSE level Geography.

B. Produced by the action of an ice sheet and / or valley glacier and so more accurately explained by the sort of processes associated with ribbon lakes.

C. Both of the above gross oversimplifications.

I'm a Geography teacher BTW so be gentle with me.

In reply to DaveHK:
it can't be 'A'(landforms are wrong), 'B' doesn't seem right so, by default, 'C' must be correct but I'm an ecologist with an interest in geomorphology so what would I know.

(somewhere back in Scotland I have an excursion guide (mid 90s) from the Quaternary Research Association for the Cairngorms which might well have the answer)

In reply to DaveHK:

Physical Geog Graduate here - I've just looked at a couple of images and I'd go for B

In reply to higherclimbingwales:

B was my thought. Obviously it's not as simple as described at the level I'm teaching it but B seems to be a reasonable simplification.

In reply to DaveHK:

but how does that give rise to the cliffs on either side ? (Craig an Dubh loch & Eagles rocks)

In reply to DaveHK:

nah, it never is as simple as it looks.

In reply to Doug:

My interpretation is that the cliffs (Creag an Dubh Loch and Eagle Rocks) have been produced by the action of ice sheet and a later valley glacier whose flow was guided by a pre-existing river valley.

There are 2 tributary valleys that join the allt an Dubh Loch above the Dubh Loch which could explain the sudden deepening below that point in terms of increased erosive power.

In reply to higherclimbingwales:

Which is why I've started to feel uncomfortable teaching it.

In reply to DaveHK:

have you looked for academic articles on the issue?

In reply to higherclimbingwales:
Yes, but only what turns up on a google search and is available without an athens login or such like. Have you got any suggestions?

In reply to DaveHK:

If you can find the titles you're looking for and ask on here if anyone has access?

I've just looked at a couple of books I have to hand & the references they quote and it seems that there's lots of publications on the northern Cairngorms but relatively little on the south (& mostly for Lochnagar), "The nature of the Cairngorms' (Shaw & Thompson 2006) suggests this is a lack in our understanding of the area.

In reply to DaveHK:

From a glaciological perspective the loch is most likely to be originally a product of overdeepening via the movement of ice during the Last Glacial Maximum.

http://bgrg.org/pages/education/alevel/coldenvirons/Cirquediagram.htm

Further to that, looking at the topography in the area adjacent to the southern end of the Loch it also harbours a moraine mound complex. These are often used for the inference of glacier ice margins and could suggest the Loch (and associated landforms) are remnants of later stages of glaciation (as is the case with most higher altitude glacial landforms in the UK) during the 'Younger Dryas' about 12,000 years ago.

So really the area the loch occupies was most heavy eroded during the LGM however it would have been extensively modified again during the YD readvance. Nice and simple! Right?

In reply to Samuel Wainwright:

Cheers folks. The reason I'm increasingly uncomfortable teaching this isn't my own knowledge but the knowledge that what I need to teach to get kids through exams is such a gross oversimplification!

The question came out of seeing the loch identified as a corrie lochan and the crag itself as an arete in materials produced by the SQA.

In reply to DaveHK:

You're right to doubt the SQA's version -- absolutely not a corrie and arete! The Cairngorms are full of troughs like this that are cut into the plateau; Loch Avon is perhaps the most spectacular example. Back when I taught glacial geomorph to the likes of Doug the accepted view was that they were carved by warm-based, hence sliding, ice streams within the North British icesheet. At less than maximum ice cover they would be occupied by outlet glaciers from a local ice cap, again capable of erosion. In this case a Mounth ice cap would also have outlet glaciers flowing down Glen Callater, Glen Doll, etc.

In reply to DaveHK:

This is quite interesting and slightly relevant to my query:

http://nora.nerc.ac.uk/20859/1/Cairngorms_preglacial_upland_AMH_26_Aug_2012...

In reply to DaveHK:

Thanks for that, I need time to read it properly but suggests that my comment that most of the published work is about the northern Cairngorms, rather than Lochnagar/Dubhloch was correct.

In reply to DaveHK:


Now you tell us. No wonder it's bollocks!

In reply to Robert Durran:

Exactly.

Also found the below on my travels which seems to be the paper that prompted the flurry of interest in the 'Little Ice Age' glacier in Coire an Lochain. Might wander up there with the paper and have a root around to see if it makes sense on the ground.

http://hol.sagepub.com/content/24/2/141.full.pdf

In reply to DaveHK:
Not sure how this stuff works these days...

Looking for access to this: http://hol.sagepub.com/content/24/2/135 which is the related paper to the one above but don't have a sage login. Anyone help?

Ta

Edit - Got it

In reply to DaveHK:

Best source of info for these things is the relevant BGS map and associated Geological Memoir.

http://www.bgs.ac.uk/catalogue/home.html

But there is rarely a clear answer. Have a look at the ice sheet animation below to get an idea of how dynamic the ice ages were (click the Download E102b2 link)

https://www.aber.ac.uk/en/iges/research-groups/centre-glaciology/research-i...

Then consider that the animation shows the last 38,000 years of a 2.6 million year series of glaciations!

In reply to Gav M:

Really excellent, thanks for posting that.

In reply to DaveHK:


I assume the SQA will also be setting the exam questions.

In which case, one would hope the answers would be what is in their teaching materials. So if you teach something different (and may be more correct), and your students reproduce that teaching in the exam, they're going to be 'wrong'...

I guess you're planning to address this error with the SQA, which would mean that, if your point is accepted, they wouldn't be able to ask any questions on the material in exams, since other, less diligent teachers might simply parrot the SQA material. Hardly fair to penalise students for learning what they've been taught, even if what they've been taught is wrong...

In reply to DaveHK:

But, to address the original question...

Looking with Google Earth, is it possible that the northern end is the headwall of the corrie/cirque, that has then been eroded later? shame that Google's image resolution takes a dive just when we need it most... You'd think they'd done it deliberately.

It's not a 'pure' glacier valley, as the are a number of partial backwalls all down the valley, running into Loch Muich. A number of merging glacial flows.

Given the number of absolute classic examples of corries and corrie tarns dotted around that example, it seems a particularly poor example to choose, given the uncertainty over its formation... The corries either side of Lochanagar would be perfect.

ps. I'm an electronic engineer who only got a B in O-Level geography, 35 years ago. So what do I know...?

In reply to captain paranoia:

I did and their answer was that the assessment in question was written by a subject specialist. Here endeth the discussion. Quite infuriating really. I made the same point you did - that there are plenty of unambiguous examples of corrie and arete in Scotland.

Your other post tallies with some of my thoughts, that the trough like feature features several drops due to other ice streams joining.

Moans about the SQA aside this has lead me to some really interesting discussion and reading.

In reply to DaveHK:

I'm also a Geography graduate.

To be fair, on the OS map it could be interpreted as a lochan and an arete. Even though it probably is not.

The SQA can't expect students to go out and look at roundness angularities and clast fabrics up there.I think they want students to just use what info they can get from the map.

Even the most up to date academic interpretation of it's formation may be wrong, as it is possible that a single landform can be explained pretty well by several different processes-maybe they wanted students to pick up on this...

None of us were there during the LGM, or Younger Dryas so we'll never know for sure.

The real issue is that I'm still unemployed!

In reply to CacCarnBeag:

Sorry can't agree with any of this. It sounds like somebody at the SQA failing to find an example of a coire. The Dubh Lochan isn't a coire Lochan, and it isn't in a coire. There is no arete anywhere in the valley and the crag itself is not a coire feature, more the side wall of a glaciated trough.

In reply to DaveHK:

No, no , no!
None of the replies are correct! God scooped it out with his hand and shed some tears for Jesus, resulting in this formation!

In reply to Skol:

God scooped it out with his hand


Strange as it may seem, that's not in the marking scheme.

In reply to DaveHK:

As ive always said if you want a textbook example of something.........look in a textbook, (not real life)!

In reply to Skol:



That explanation is beautifully simple. Henceforth I shall teach that instead.

In reply to DaveHK:

I'm not godly, but get poetic at around 2359