h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Well.
After 6 months or more of digging in our valley-bottom shaft, things are changing a bit.

Total material removed maybe 10-20 tons. Various metalwork and a ton or two of cement and sand is holding the walls together and the roof up.

Thus far the cave has been a bit odd - the initial shaft had loads of washed-in rock and soil to remove, then the walls needed stabilising, and then the capping could begin. Strangely, given the amount of rock microblasted out of the cave, little of the wall surface shows signs of blasting, since rather than widening out a standard bedrock cave, this one had walls consisting of large in-situ broadly cuboid blocks that had been eroded around to the point of no longer being permanently attached to the bedrock. They still needed cracking into small pieces to haul out of the entrance, but did leave a tidy and natural-looking cave behind them.

We know where the water goes - to a cave in the hill the other side of the (small) valley the dig is in, but the way on isn't easy.

Now we seem to have encountered a region where a space above is loosely filled by disordered boulders that aren't in situ, and are too large to have come in the way we dug down, so it seems we've either broken out into the bottom of an old shaft to surface, filled with surface debris, or into the side of a pre-post-glaciation-infill gorge that used to be the valley bottom.
If the latter is the case, the dig is probably dead, but I hope it's really just a shaft of loose rock that we can find some safe way around the bottom of.

However, the fact that there was flood debris on the scaffolding in the roof of a wide part of the cave that was about 2m high and 1m wide, and about 4m above the current cave bottom does show that the potential for serious flooding is there. In an ideal world, there'll be a small constriction downstream somewhere that can be easily emoved, but digging is rarely an ideal-world sport.

After some more excavation, assisted by a power-washing fed by siphon from the stream above, it looks more clearly to be a shaft. Stabilising it could be a problem, but some digging in the passage floor just before the shaft raised some hope of a safer way on through the shaft at a lower level where shoring might be more practical.
It's still far from perfect - the left-hand wall where we're digging down seems to be yet more in-situ stacked blocks and slabs rather than actual bedrock.

After a few weeks of small trips widening the passage, there are now several cubic metres of rock waiting to be hauled out, tomorrow evening if enough people turn up. Maybe then we can get a better idea of just how bad the end section is.

The potential up-side is that *if* the new shaft at the end used to be a significant water source, the passage may be wider downstream from it, and going could be easier. Fingers crossed.

I have to wonder, dear, why you're a jobhunting C coder and not a jobhunting potholer?!

*apologises for not noticing post earlier*

Unfortunately, there aren't any professional positions for potholers

Following from the previous Wednesday (when I was off skiing), when some 120+ bucket-loads of rock were hauled out, largely filling in another substantial stretch of the original streambed, last night was mainly hauling.
We probably shifted about 70 loads, including 20 buckets of wet mud and gravel from the far end of the cave which was spread over an older area of spoil in the hope it might level the surface and maybe encourage grass to grow later in the year.

We also trialled a couple of new buckets. The old 2 gallon/10 litre ones were too small for many rocks, which had to be hauled up using tape slings. With some shapes of rock, this wasn't too bad, but somewhat rounder boulders were a little precarious, and sometimes we ended up with someone climbing up beside them to help make sure they didn't fall out of the slings.

A new 25 litre rubber bucket (the same traditional bucket style as our old 10 litre one) proved excellent for hauling the large roundish or cubical rocks, but had a couple of minor drawbacks.
a) Being essentially a scaled-up bucket, for someone of my build (short legs, long arms) it was almost impossible to carry bucket-style in one hand over uneven ground, since the bottom would drag on the floor.
b) When half full of rock, it was too heavy to lift to any higher position. When full of rock, it was too heavy to lift at all.
If you imagine an eight-year-old child trying to carry a regular bucket full of rock, you'll get the picture.

However, considering it less as a bucket per se, and more as a device simply to raise rocks to ground level, and then lifting them out at the shaft top for transport to the appropriate place, it was a definite success.

We also bought a ~25 litre rubber trug, and I tied up a hauling harness from thick 25mm nylon tape to support the base. When loaded the tape pulls the handles together, helping to close the top, and this should be ideal for lifting large rocks the wrong shape to fit into the other large bucket.

Compared to the old sling route, the large buckets should greatly speed up the removal of large rocks, since it can take quite a while to rig tapes round a rock in a way that looks even reasonably safe.

http://news.bbc.co.uk/1/hi/uk/3581031.stm

What do you think is the deal with this situation?

From what I understand, the scientific/exploration 'problems' with visas are invented. I'm not sure how many cavers go to Mexico (from Europe at least) just to go tourist-caving (caving in already explored cave passage) - I suspect that most go there intending to explore, often in collaboration with local clubs, as indeed this trip was.

Actually, I know one of the guys (Jonathan Sims) who was trapped underground. He was in my college caving club 20 years ago, and has recently retired from the Army. He's been caving in Mexico very frequently, and without any visa problems until now. He reckoned the press furore was mainly down to there being not much else news around at the moment, possibly exacerbated by the fact that he was the only Spanish speaker (the Mexican caving contingent left before the problem arose), and so the above-ground team couldn't easily do much to head off press speculation.

He reckoned the Mexicans had to redefine caving as scientific activity in order to legally expel the cavers, and they might have to reverse that redefinition fairly soon, since the local economy makes quite a bit of money from foreign caving expeditions. He said that the local rescue people were quite happy to have foreign divers do the rescue, since it was rather serious for anyone but the most experienced cave divers. Incidentally, Rick Stanton, one of the divers, is also a passing acquaintance, being a member of my Yorkshire caving club, and I probably know the other diver by sight, if not by name.

The 'uranium' thing seems entirely bogus. To date a cave from calcite samples (bits of stalactite or suchlike), it is *possible* to use uranium-thorium dating to get a good age esitmate, since tiny amounts of natural uranium are incorporated into the calcite when it is deposited, but in such vanishingly small amounts that you need a mass spectrometer for detection and measurement. I very much doubt that this team would have been doing anything like that, since they were into exploration, rather than science.

The 'military' question is a joke - like someone said, if a Mexican soldier wanted to go camping in the UK, he wouldn't need a special visa to do it. The only training aspect of the trip would have been physical training and leadership stuff, nothing more than civilians going on a 'character building' outdoor course.

I can only assume there were larger political reasons behind the reaction of the Mexican government. The press reaction seems quite ridiculous, even for someone used to British tabloid excesses.

I'm off to Yorkshire this weekend. If Rick is around, I dare say I may have a bit more first-hand information next week.

Interesting.

Canada is the only place you've come so far on this side of the globe, right?

Canada's the only place I've *caved* over there. I did do a couple of weeks of volunteer trail maintenance in Colorado a few years ago.

May update:

The floor of the shaft from January was excavated down by several metres, and metalwork installed to support the looser wall elements. The way on proved to be under the least reassuring shaft wall, and the chamber beyond looked rather worse than the shaft had done, with various boulders with uncertain foundations, and the right-hand chamber wall being the base of a loose pile of mud and gravel. A way on forwards was visible, with a small (~6 inch) passage going on and down for some distance.
It was decided that the safest route was to dig down in the chamber floor beyond the shaft, progressing from mainly capping and rock-shifting to bucketing mud and gravel out from the wet chamber floor. This requires a bucket-chain from the increasingly distant cave end to the surface shaft bottom, and ideally 7 or 8 people.

Yesterday night, a party of 6 moved 56 buckets of muddy gravel, and another 20+ buckets-worth of rocks from the cave end to surface, which was rather tiring. There are several short drops in the cave, and the section I was in involved reaching down an arm's length to lift the bucket from the person below, manourving the bucket up a few twisting steps, and then lifting it to place it on the floor of the passage above, which involved moving it up through a gap not large enough for both my head and the bucket. This meant either having to slowly push the bucket almost to full-stretch above my head (tiring), or a more dynamic method using the momemtum from an initial hard pull (risking bashed fingers if my aim was off).
However, a definite route on was seen, though a still-unstable right wall requires more work. The current impression is that the unstable stuff is an infill of loose material that is unlikely to be structural, so digging should eventually remove it as a problem.

The extracted mud and gravel was used to good effect attempting to cover some of the spoil on the surface, and the hope is that the mud will be a good foundation for grass and heather to help make the entrance look more natural.