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From an article in New Scientist for Dec 29, 2001, p. 58 During WWII a number of US warplanes en route from Labrador to Iceland were forced by storm to land on Greenland. All the airmen survived, but the planes sank into the ice, until by now they are 80 meters, about 250 feet below the surface. A team of adventurers has recovered one of the P-38s. After managing to find the location, they sank a shaft down to the plane, and then descended to it by " abseiling" down to it. I knew this was a rock climbing term, and found a site of rock climbing terminology. Perhaps the terms might be worth discussing. http://www.theclimbershub.co.uk/dictionary/dictionary.asp?Term=abseil
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A synonym for abseil is rappel - and you'll find this word is the one used most by the people that do it.
To climb up a rope with the aid of a friction device is to prussick. Couldn't find this at the above URL.
I did a fair bit of both in my younger days - but mainly into old mines. As I recall there were a lot of european terms - not surprising considering the origins of climbing as a sport. Words such as carabiner (snap clip for tethered or free running ropes) and piton would be known to most. Considering lives are involved, the huge amount of technology behind the development and manufacture of climbing gear (and hence its cost) are also not surprising.
stales
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Dear Stales: Rappeling and abseiling are both means of descending in a controlled manner. The abseil mentions use of a figure of eight. I gather that the rope goes about the person in a way that rate descent can be controlled, but can't imagine how the user prevents fouling or excessive tightness.Or worse still, sudden loss of control.
The chimney down through the ice apparently gave very little freedom of movement.
I haven't finished the article yet, so don't yet have any idea how they were able to dig a chimney big enough to lift the plane straight up two hundred and fifty feet! Incidentally, that means the planes sank five feet a year, meaning the ice isn't as solid as you might think.That's almost two tenths of an inch per day.
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A 'Figure of Eight' friction device is two loops of a special aluminium alloy about 3/4" thick joined together. 'Chunkiness' is important because the heat from the rope passing around the device needs to be disseminated through it - or the heated device will melt its way through the rope if the rapeller stops during a rapid descent. One end of the device clips via a carabiner ("crab") to one's harness, the other hangs free. A rope is passed once or twice around the outer loop then across the throat of the device, between the two loops. The rapeller holds onto the upper part of the rope (if descending backwards - the least terrifying way!) and grips the free end of the rope behind their buttock. If they're using the correct configuration of rope, descender and turns around the device, little more than a strong handshake grip is sufficient to control their descent.
For the record, and despite their popularity, I believe Figure of Eight descenders to be potential killers and won't use one. A guy died on a cliff near my place because his Fo8 snapped across the middle whilst he was descending. When this happens you are left with a useless loop on the rope - and not connected to you, so down you go. I always used a 'whaletail' device instead. These are a block of alloy, rectangular in section and about a foot long. Along one edge are a series of protruding 'whaletails' - lipped wedges - around which the rope passes. Much safer, far greater heat sink capacities and, even if a wedge or two snap off (never heard of it happening), there's still a few left to get you to the bottom. The construction of a whaletail also lets one tie themselves off during a descent if they need a rest or if they need to use both hands. Difficult/suicidal with a Fo8.
As you say, the rope must hang free. A big step to ensuring this is to use a braided rope rather than a 'wound' rope (ie twisted). The rope consists of a core of tiny kevlar or nylon fibres, only thousandths of a millimetre thick, each as long as the rope itself. They are held together by a woven braid casing. (I recall a previous discussion on ropes - in relation to casement windows). The rope itself will be rated not only by its breaking strength, but also by its 'bounce' factor. Climbers require ropes with a high stretchability so they won't be pulled up hard if/when they fall. A rapeller on the other hand doesn't want a bouncy rope, it makes descending unpleasant and difficult to control (hence less safe).
Ropes are carefully coiled in a special way, rather like plaiting, and packed into bags. Done properly, the rope will undo itself without kinks or snags if it (and its bag) are tossed from the anchor point at the top of the descent. Looping them like a cowboy's lariat is guaranteed to induce loops and tangles and therefore not regarded as a long term practice in the field. They should also never touch the ground or be trod upon - the tiny particles of dirt will chop their way through the braided wrapping.
Rapelling with only a rope is achieved by wrapping the rope around your limbs and trunk and using clothing as padding. This is highly ineffective with a braided rope (they are made to operate with a low coefficient of friction and hence extremely difficult to grip), and more easily achieved with a wound rope. Only for emergencies in my opinion.
BTW - The bottom end of the descent rope should have a large knot tied in the end so the person doesn't rappel off into space. A sky diver friend of mine has however rappelled off a rope at 10,000' from an aircraft!
stales
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The chimney down through the ice apparently gave very little freedom of movement.
Okay--in a mine, I think what you're describing is called a shaft. Why is it a chimney, here, please?
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Dear Jackie: there is a very extensive list of climbing jargon. Chimney is just one word I have seen for a narrow vertical passageway. Just search for "abseil" and see how many sites there are! "Seil" is German for rope, and "abseil" just means to go down a rope. As Stales' very informative post indicates, there are a number of different kinds of rope, and different kinds of devices to control rate of descent. Not for me.
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> Why is it a chimney, here, please?
Thanks for the reply on this wwh - spot on.
Y'all may like to know that climbing has also spawned 'chimney' - the verb - ("We'll have to chimney that section of the climb"). This style of ascent or descent is where the climber braces their back against one wall of the chimney and locks their legs against the opposite wall - movement being afforded by little shuffling steps up or down. Hence 'chimneyed' and 'chimneying' as well ("Joe took the lead while we were chimneying that section").
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Pooh-Bah
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[Bob Rivers]
There's something stuck up in the chimney
And I don't know what it is,
But it's been there all night long.
Well, I waited up for Santa all Christmas night
But he never came and it don't seem right.
And there's something in the chimney
And it doesn't make a sound,
But I wish you Merry Christmas.
There's something stuck up in the chimney
And I don't know what it is,
But it's been there all week long.
Well, the dog keeps barking up the chimney flue
And we don't know what we're going to do.
Cause there's something in the chimney
And it doesn't move around,
And it's been a week since Christmas.
There's something stuck up in the chimney
And I don't know what it is,
But it's been there all month long.
Well, it's jammed up tight above the fireplace
Now the house smells funny, such a big disgrace.
That there's something in the chimney
And it doesn't talk at all,
And it's been there since last Christmas.
There's something stuck up in the chimney
And I don't know what it is,
But it's been there all year long.
I'll been waiting up for Santa like I did last year
But my brother says, "He's already here."
And he's stuck up in the chimney
And he doesn't say a word
And he'll be there every Christmas.
And we'll have him every Christmas.
[/Bob Rivers]
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It's been dunnamany years since I did any abseiling. But others have tried ... Below is a synopsis of a Darwin Award-winning prison escape attempt in the US a couple of years ago. The Darwin Awards, for those of you who don't know, are awards handed out to deceased people who have managed to remove themselves from the human gene pool in bizarrely stupid ways. The Awards are managed by one Wendy Northcutt who has a website at http://www.darwinawards.com. She has also published, I believe, two books' worth of award winning deaths, honourable mentions and urban myths on the subject. Well worth a read as well. This tale comes from the first book. A prison in a new, high-tech prison decided that he could escape from it through a window if he managed to tie enough sheets together. He did quite well in that area, because he got enough sheets to make a "rope" that was about 100 feet long. Timing it just right, he smashed his way through a toughened glass window, tied off one end of his "rope" and flung the rest of the bundle out the window. Clambering carefully over the broken glass on the lower rim of the window, he trusted his weight to the sheets and began the perilous climb down. Unfortunately, that sharp glass was having an effect on his "rope", and his weight dangling below the window enabled it to cut through the sheet draped over the window frame. Our intrepid escapee fell to his death on the concrete below. Sad? Well, maybe. But one can't help but wonder what would have happened in any case even if he had actually managed to get to the bottom of the makeshift "rope". It was, as mentioned above, about 100 feet long. The drop to freedom was, unfortunately, 180 feet ...
The idiot also known as Capfka ...
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I remember following the progress of the expedition to recover the P38 from the icecap. I don't remember it being 250 feet, but I can't argue, since I no longer have the Flight magazines that were chronicling the recovery. But Stales is right in making the assumption that the majority of the overburden was deposition rather than the aircraft "sinking" into the ice. They did some studies at the same time as I remember it.
In Zild there are two glaciers, Fox and Franz Josef, which are apparently unique in that they descend to nearly sea-level in a temperate country. At various times I've been to the neves of both of them. They rise, very steeply, to about 8,000 feet. Both of them have huge neves, heavily crevassed last time I was there. They drop so steeply that the icefalls are spectacular and damned dangerous to climb, to boot.
Glaciers are fed by snowfall in the neve as Stales says. If there isn't much snow for a few years, the rate of flow falls away. In the case of Fox and Franz, this has been the case now for about twenty years, and they have actually both retreated up their valleys about seven miles. The retreat is caused by melt-off (which everyone blames on global warming) but for a number of years before (I think) 1975 they were actually advancing at quite a rate. It's a balance between attrition and deposition, and at the moment attrition is winning hands down.
The local geologists have a field day (literally) at Franz and Fox, because almost all of the glacial landforms are there, raw and fresh, just begging to be studied. Whatever turns you on, I say!
The idiot also known as Capfka ...
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Dear Jackie: When they got Glacier Girl out, she was taken to Middlesboro, KY. Did you know KY has three "astroblemes"? One is near Middlesboro,Bell county.
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Hi, Dr. Bill--no, I don't even know what an astrobleme is.
And stales, perhaps you can help me here, or you, CK--I'd had the idea that a chimney (vertical, narrow, yup) was something that was formed naturally--usually in rock. But I thought the fact that it was dug would qualify the opening down to the plane as a shaft. Otherwise, why don't we say, "going down the mine chimney"?
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The idiot also known as Capfka ...
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Dear Jackie: I thought you'd never ask! An "astrobleme" is a "star wound" where a large meteorite hit the Earth long ago, leaving an elevated ring around a crater.
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Happy to oblige, Mr. Pronounces-his-t's-half-the-time!  "Star wound" = "astrobleme" = star blemish, right?
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A chimney in the non-building sense is always a natural feature. However, one can use the climbing technique of "chimneying" to make one's way up or down a man made structure.
A mine shaft is a vertical or subvertical opening used for transporting people, equipment or rock to and/or from the surface. The term is often used incorrectly in reference to a horizontal or subhorizontal tunnel opening out onto a hillside. The correct term is adit, the opening of which is the portal.
Horizontal tunnels throughout a mine are referred to as drives.
A couple of special case of shafts are winzes and raises (or rises, depending where you're from). Both words, like chimney, can be used as a noun or a verb.
A winze is a shaft developed (ie excavated) downwards from a drive - it is not open to the surface.
Similar deal with a raise - only it is developed upwards from the back (ie ceiling) of a drive. Purists will take exception to this because raise boring machines actually develop the raise from the top down. A mere technicality, the hole is still called a raise. Raises may be developed through to the surface, particularly if they are to be used for ventilation (hence vent raise) and/or if they are to be used as an escapeway.
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addict
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You're just loving this thread, aren't you? 
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Follow me on the subject of this post? wwh suggested off board I give "astroblemes" the treatment.... I am fortunate to be friends with Drs Jenny and Alex Bevan - wife and husband - and curators of the UWA E de C Clarke Geology Museum and The Minerals and Meteorites department of the Western Australian Museum respectively. A quick call to Jenny helped answer to a very good question from wwh - namely, "How can one calculate the size of the celestial body that created an astrobleme from the size of the crater?It seems that the answer isn't simple, the crater's size depends upon a number of variables (see green text below). Frinstance, Jenny said that the Hoba meteorite, a 60 ton lump that landed in Africa, left no crater. Jenny's emailed reply was as follows: This is a useful page:
http://seds.lpl.arizona.edu/nineplanets/nineplanets/meteorites.html
The diameter of a crater should vary with the cube root of the mass of the impacting meteorite times its velocity squared, but it will depend on the nature of the body and impact site and angle of trajectory.
Impact craters less than 1cm across are found on other bodies in the solar system and are called microcraters (not on Earth, meteorites this size burn up in atmosphere).
Impact craters larger than 300km are called impact basins (again, not on Earth because they date back to early times and Earth processes have obliterated them)
Earth processes work on craters of all sizes to obliterate them. eg. a crater 20km across will be recognisable about 600 million years, whereas craters 1km across will only be recognisable for say 1 million.
An ASTROBLEME (= "star wound") is the eroded remant of an ancient impact crater eg Goss's Bluff. We tend not to use the term once we are sure about it having been a crater, and just say that it is an eroded and/or buried
crater etc., which is probably why you couldn't find a definition easily.I've checked through the site mentioned above and found it chock-full of good info. I also found a site dedicated to the Barringer Crater in the US but didn't note the URL.  It's interesting because, in the early 1900's, Mr Barringer basically did his shirt drilling the base of the crater to find and exploit the fabulous wealth of nickel, iron and diamonds he presumed lay buried. He did not take the news provided by a ballistics expert very well. This chap's experiments showed that any sizeable body travelling at cosmic velocity is completely unaffected by our atmosphere - but totally destroyed the nanosecond it impacts the Earth's surface. So Mr Barringer was looking for something that wasn't there. stales
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doc - am I so transparent? I just hope others are enjoying it as well. Tis a sad day the day one doesn't learn something. Rest assured, I'll pipe down when I hear the moderator's bell!
Besides, it takes my mind off the cricket. [tag for CapK and Max e-]
This thread is just like my mind...full of words and ideas, interested, interesting, many themes, a bit of adventure etc!
stales
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Dear Stales: thanks for the link, which I will have to study. One more question. There have been a number of studies on very large methane hydrate deposits on seafloor reported on Internet. When I saw map of Chicxulub crater on Yucatan extended well out into Gulf of Mexico, it occurred to me that a very large amount of sea floor methane hydrate could have been vaporized and ignited, contributing a very large amount of energy to the impact. I sent an e-mail to scientist studying the crater, and he replied that the idea was new to him. I subsequently found one site not written by a scientist mentioning the possibility of methane hydrate having been ignited. It seems to me that methane hydrate might also have produced a large amount of soot that could have blocked sunlight, contributing to long winter and extinctions Please comment.
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Timely Q wwh....
A geological bookshop near me just closed down and was getting rid of everything at ridiculous prices - including $0!
Among other titles (including The SAS Survival Handbook!!), I got two copies of "Evolutionary Catastrophes - The Science of Mass Extinction" (Vincent Courtillot - trans. by Joe McClinton, Cambridge University Press, 1999) It's a slim volume and a relatively easy read, strongly geological, but followable - pay the postage and you're welcome to the 2nd copy!
M. Courtillot gives fair treatment to all the prevailing hypotheses on the subject. Basically there's two schools - those who promote cosmic impacts and those who prefer a terrestrial source - including Courtillot - and now stales. He believes vulcanism the likes of which has not been seen in modern times was a more frequent offender than impacts. To quote:
"....every 20 or 30 Ma (million years) or so, an immense bubble of material from the mantle becomes unstable, rises to the surface and bursts. Its emergence triggers gigantic explosive eruptions and finally lays down millions of cubic kilometres of basalt within a few tens or hundreds of thousands of years. Some ten (sites) have been identified from the past 300Ma. Seven of them coincide with seven mass extinctions, and in particular with the two largest ones (including the Cretaceous/Cenozoic ("KT") boundary often attributed to the Chicxulub impact).........Eruptions of such magnitude seem able to affect the biosphere by injecting ash, aerosols, and gases - and they can probably cause darkness, temperature variations and acid rain. It is clear that rarely, but sharply, the internal dynamics of the globe affect the evolution of species.......No doubt it's hard for human beings to imagine the end of the species they belong to, or to concieve that over 99.9% of the species that ever lived on Earth are already extinct. (My emphasis).
Courtillot cites evidence that the Chicxulub impact occured during one of the episodes of vulcanism. He concludes that it may have contributed to the unhappy state of the planet but that it was not the causitive event.
His book is a brave attempt to reconcile the schools of thought. Since the 1980 article about Chicxulub in Science there have been 2,000 papers published on the subject!!
stales
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Dear stales: In the past year there have been quite a few papers about possible role of methane hydrate in the KT catastrophe. I saw a paper describing massive sediment slump off Norway 8,000 years ago that must have sent a huge tsunami towards British Isles. And I have seen a couple papers saying deposits off North Carolina could slump, and tsunami could devastate large part of east coast US.
But if I remember right, the presence of iridium at KT boundary cannot be attributed to volcanism.
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pay the postage and you're welcome to the 2nd copy!
stales, if dr. bill passes on that offer, I call dibs -- PM me please!
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wwh - Correct again - the presence of that much iridium is a sure indicator of asteroid impact. As mentioned in the previous post however, the impact was during an event of tumultuous vulcanism. The Ir rich layer occurs in the midst of a huge thickness of basalt flows, indicating it was not the cause of the vulcanism. Courtillot postulates that the material released into the atmosphere during the volcanic event exceeded that of the impact.
stales
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