Not Another Challenge Activation Report

Back to the lower bands and a good long walk:

[Moel Hebog - About as hard as I could make it][1]

Route Rhyd Ddu to Moel Hebog via Moel Lefn and Moel yr Ogof.

Could any of the geology experts here tell me something about these mountains?

I was impressed by the really bubbly rock that comprises the summit of Moel Lefn:

Coming down to Bwlch Meillionen off Moel yr Ogof the rocks are an odd concretion, cut through deeply:

45 QSOs logged - a bit different from recent 10-m activations!

73, Simon
[1]: G4TJC: Moel Hebog

Hi, Simon, unfortunately I lost my geological map of that area and haven’t replaced it, so this is off the top of my head. The bubbly rock used to be mapped as an acidic lava called rhyolite (characteristic of the Andes) but is more likely to be an ignimbrite, a thick deposit of volcanic ash which was hot enough to weld together, ejected from the Snowdon supervolcano which had a crater several miles across which is no longer visible on the ground as it got covered. The bubbles are only on the surface, due to differential solution of the minerals by slightly acidic rainwater.

The “concretion” is interesting, I would guess that it was either deposited very close to a volcanic vent or is the infilling of a vent after eruption, a “vent agglommerate”, but I would have to go and look at it.

That was a good outing!


You may have missed them but on the lower slopes are the famous Aero chocolate mines.

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Dammit, now I’ve got to clean the screen again!


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Thank you Brian. We certainly have a good variety of rocks around here. And much effort has be expended digging into them by generations of quarrymen and miners. It’s good to get some incite into how they came to be. Sounds like a very unhealthy place to stand, back in the day!

Richard, you may be thinking of the nearby disused cinder toffee geyser. Sadly this ceased production when the Welsh confectionery industries bubble burst.

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Great report Simon and looks like a good route. The clouds over Snowdon are lenticular clouds created in the eddies that form over mountain tops. Used to see them a lot when I lived in North Scotland.

73 Glyn

Many thanks Glyn. I’ve seen the flying saucer type once or twice but this whispy dark sort was a first for me.


These dark whisps are contrasted on a background of cirrostratus clouds, against a blue sky they would be white.

In the report you ask about the cave. This is clearly visible from the top boundary of the Beddgelert Forest: There is a large very prominent steep rock buttress standing out in the middle of the line of crags, the cave is a horizontal slash not far below the top, reached by an airy traverse from the right hand side looking out. The back of it contains a seam of asbestos, the same seam that was trialled unsuccessfully on the summit area. The cave likely formed from the erosion of this mineral.


Oh rats! - that’s something else I missed. I’ll have to go back. But then I found a picture of the approach to the trial…

… I’m not sure I’ve got the bottle for that one.