Convex Slopes And Waterfalls
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Wild camping in the Black Mountain range in South Wales at the weekend (not to be confused with Black Mountain which is in the Black Mountains a few kilometres to the North East – easy eh?) and I had one of those moments that remind you to keep your wits about you.
We were coming off a ridge down to where a friendly farmer had allowed us to stash the car in his barn for a very reasonable sum. It was one of those rolling South Wales ridges with a sharp scoop out of the Eastern side formed by glaciers during the last ice age.
I was carefully picking my way down a steepening grassy slope and sure enough called back to the others behind me that it looked like we’d started down a too early and had met a little rock-step.
I could see the top of a rowan poking its branches above the grass a few meters down-slope. They often don’t get much more than four to six meters tall in the mountains, since they’re blasted by the weather, so I figured it was a four or five metre drop.
There was a fast running stream, a few meters to my left and slightly behind me so I went down another couple of meters to look at it running over the edge.
And froze – I was about three meters above a vertical cliff that was around thirty meters high. Easily ten times higher than I’d guessed from the rowan.
I wasn’t in any appreciable danger, I was already “highly averse” to falling off what I’d thought was a four meter rock-step so wasn’t pushing my luck. It was just a bit of a surprise!
The waterfall had a very reliable “counter slope” just beside it that was bedded on very solid rock. So I went back up, before coming down onto that and stared down at the water pouring into space. Which really was one of the most impressive sites I’ve seen in a while and therefore, to me, well worth being in that spot. (Believe me – the picture shrinks the drop massively!)

As usual when looking at a drop like that, some words from a Summer Mountain Leader (“ML”) course came back to me. “One of the particular dangers of the Welsh mountains is their convex slopes. Meaning that as you walk down, you can’t always see the terrain ahead of you getting steeper and steeper, until you fall off it!”.
It just made me think that without being subconsciously aware of that particular danger and without consciously keeping my guard up as we happily ambled back to the car things might, just might, have ended up rather differently.
On the way there we’d listened to one of Podcast Bob’s offerings (Mountain First Aid 27/2/07) where he interviewed Wayne Thackery of Woodhead Mountain Rescue Team. Wayne said that in his experience although many, many people go in to the hills without proper gear most of those get away with it “by the skin of their teeth”.
Whereas, of the people who go in with experience and proper preparation, the ones that get caught out are generally coming off something after achieving their objective for the day. They just let their guard down (which might sound familiar to one of the this year’s HR crew…)



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