[shark]

At the Tor today the topic came up of how it seemed to be that seepage points change at the crag - for example Bens Roof used to be the last thing to now and now never seems to get wet. Also black streaks at the crag may be indicative of former seepage points that actually don't get wet now. .

Stone suggested that the cause maybe that the seepage points get silted and therefore the water finds a point of lesser resistance elsewhere thereby creating a new seepage point.

Seemed like a plausible explanation.

[lagerstarfish]

also, the water dissolves new holes to head down (or existing ones get bigger) - see the ex-waterfall at Malham as an example of this

[lagerstarfish]

besides which, Stone is crackers

[tomtom]

Silting up is along the right lines but probably not always right. Karst seepage can stop when the calcium carbonate is precipitated out. Also - there is the bio-geochemical action - where algae - goop - snot like substances can act to fix and create limestone.

Also water may have many different ways of getting through to the face - more of a maze of cracks and seeps than one clear route.

All this comes from working next door to a carbonate sedimentologist who is also a caver...

[andy_e]

Could also be due to larger scale changes in the catchment, for example removal of trees or digging a drainage ditch somewhere above the crag...

[tomtom]

Or the cumulative action of all those portable drying fans whirring away :D

[Wil]

I'd always assumed that water was automatically attracted to the crux of whichever route I'm trying, but some of these theories sound more plausible.

[36chambers]

I'd always assumed that water was automatically attracted to the crux of whichever route I'm trying, but some of these theories sound more plausible.

I'd keep an eye on the people you're climbing with.

[DAVETHOMAS90]

Could also be due to larger scale changes in the catchment, for example removal of trees or digging a drainage ditch somewhere above the crag...

That's what's affecting the routes at the left hand end, isn't it?
Certainly seems to have increased the amount of algae.

Perhaps a new drainage channel will affect the balance of drainage elsewhere on the crag - drawing it away from Ben's etc.

[SA Chris]

Fracking the crag will sort it all out.

[shark]

I'd always assumed that water was automatically attracted to the crux of whichever route I'm trying, but some of these theories sound more plausible.

I'd keep an eye on the people you're climbing with.

Hateful when you discover people have pissed your projects