I haven't seen that suggestion. Obviously the bottom reaches would be, but the further in the Black Keld sump goes, the steeper the gradient would be from mossdale. But then 150m/5000m (if those are correct) is only an average gradient of 1.7 degrees...

see above post

I happen to have a copy of RRPC10 here on the other side of the planet. Hope I'm not infringing any copyright, but here's the bit about the follow-up trip in two phone pictures.

We live, apparently, in an information age. (Yep, heading swiftly for disinformation, but whatever...) Isn't it interesting how feeble our information age is (how many google searches were used in this thread?) when we peer backwards in time. We find a blank wall... at least, on the slopes of...

Ah.... I see there's a whole rabbit-hole around wife-holes. With no clear answer, but thanks for alerting me to that thread.

Moderator comment: This thread split off from https://ukcaving.com/board/index.php?threads/tatham-wife-rigging.33019/#post-410249 OK, a deviant follow-up question not about deviations : Why is it Tatham Wife (or, eg, Batty Wife) ? What's with all the shakeholes being called "Wife". I think I...

As Paul explained, it's a large cave in North-West Nelson, New Zealand. Now the bottom half of a 1200m deep 2-3 day through trip. As well as good earthquakes (& good caves), NZ also does good nettles - the sort that can kill a man/horse, and makes english nettles look rather prim & pretty. The...

In general, sub-surface shaking is less than on the surface. Think of how much the top of a jelly shakes compared with the inside, away from the free surface. A large EQ in NZ (1940s?) wasn't felt much in a deep mine on the west coast, but those looking up the shaft could see daylight being...