A Level Glaciation in Cwm Idwal

I live just down the road from Ellesmere College, where I used to teach, and for the last few years they have asked me to take a group of 6th form Geography students into Snowdonia to look at glacial features. In previous years, the trip has been near the start of their time studying glaciation but things slipped a bit this year due to clashes in the school calendar. As a result, the purpose of this trip was mainly allowing the students to get a realistic feel for the scale of the features they had already studied as well as provide a little revision.

Happy not to be in the class room
Happy not to be in the class room

Cwm Idwal is a fantastic venue for glaciation trips, due to the fact that it is so easily accessed from the road and there are so many features contained within a relatively small area. The recent weather also gave the trip a touch of realism with snow under foot. It’s also amazing to think that this area would be able to sustain snow throughout the year if the average annual temperature was just 2-3 degrees Celsius lower than at present.

We were able to look at various features: the corrie itself, tarn, corrie lip, moraines, striations, back wall, col, diffluent col, syncline, alluvial fan, roche moutonnee, arete, U-shaped valley, spur, truncated spur, ribbon lake and probably a few more. We were also able to talk through some of the changes that would have taken place since the retreat of the glaciers and some of the things that are being done to reduce man’s impact on the area.

Looking down the corrie from the back wall
Looking down the corrie from the back wall

Although there was plenty of snow about, the conditions were very kind to us, enabling me to take the group as far back as the back wall of the corrie to get a feel for the size and angle the ice had carved out of the rock. I also find that it’s a great place to stand and imagine glaciation in action as the whole scene is laid out before you.

After many years of erosion, it’s hard to imaging quite what things would have looked like without the downwashed scree, soil and vegetation. The tarn is now an average of only 3m deep, with a lot of rock in the bottom. The lower sections of the back wall are significantly levelled off with all the rock that has fallen off in the meantime and been covered with vegetation.

However, it was a very productive trip, on a beautiful day to a great venue. Fantastic.

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