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5.0 KiB
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<meta http-equiv="Content-Type" content="text/html; charset=utf8" />
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<title>CUCC Expo Surveying Handbook: What is a cave survey?</title>
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<link rel="stylesheet" type="text/css" href="../../css/main2.css" />
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<style>figure {font-weight: bold; font-size: small; font-family: sans-serif;font-variant-caps: small-caps;}</style>
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<h2 id="tophead">CUCC Expo Surveying Handbook</h2>
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<h1>What is a cave survey?</h1>
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<p>This may seem like a trivial question - most people who have been caving a
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few times have used cave surveys and can get some feel of what the cave is like
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from them. But what actually goes into the making of such a "map"?</p>
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<div class="onright">
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<figure>
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<a href="/expofiles/surveys/290-291-295/290-291-295-PostExpo2022-Output1Jan2023.png"><img src="290-291-extract.jpg"></a>
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<br><figcaption>Part of the Fischgesicht finished survey for 1623-290/291 (2022)</figcaption></figure>
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</div>
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<p>The idea of the survey is to produce a map of the cave that is accurate,
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useful for route finding and possible connections (and look pretty). Enough
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detail needs to be recorded that every passage is recognisable, whilst those
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drawing up the map are aiming to convey a good overall view of the whole cave
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- including structure that may be far from obvious in one individual passage.
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The survey should also serve as a basis to "add value" like geological
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information and clues to how the cave was formed. Some of these aims conflict
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with one another when the survey is drawn up, but this is part of the "art" of
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survey drawing.</p>
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<p>Recording the data in the cave is fairly straightforward, if time
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consuming. It does help to have an idea of how all the details that you
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record will be used. To this end, everyone is encouraged to draw up a survey
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to better understand the difficulties and thus to improve the standard of
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recording.</p>
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<p>The basic survey is simply a series of <b>straight</b> lines connecting a
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number of points together. This is constructed by measuring the distance
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between points, and taking a compass bearing and clinometer reading from each
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point to the next. It does not matter which end these readings are taken
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from, as long as the notes make clear which end is <b>from</b> and which is
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<b>to</b>. Taking readings from alternate ends, called <b>leapfrogging</b>,
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is often the most efficient way to proceed, and helps mitigate <b>some</b>
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systematic errors. (ie. start 1 to 2, then 3 to 2, 3 to 4, then 5 to 4, 5 to
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6 etc.)</p>
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<p>Around this centre-line we need to draw passage detail in both plan and
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elevation - recording the dimensions and sketch of the cave. Easy.</p>
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<figure class=onright>
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<a href="nutshell.jpg" border=1><img width=100% src="nutshell.jpg"></a>
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<figcaption>
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Survey Workshop - <a href="/expofiles/presentations/cave_surveying_20130626.pdf">slides</a>
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</figcaption>
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</figure>
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<p>However, the amount of information collectable is infinite and due to cold,
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impending exhaustion and rapid approach of call-out or derigging, time may be
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short. The handbook (in "<a href="how.htm">Methods: underground</a>") sets out
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what is considered the essential information and a few ways to
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collect it. Teams of two or three are used. If there are two of you it is
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generally accepted that one reads the instruments while the other writes it
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down and sketches, each person finds their own survey station. With three,
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two people can do as above while the third scouts for stations or one can do
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the instruments, one records the figures and the third sketches.</p>
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<p>A survey party will never survey everything they see - but you should take
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particular care to note junctions, inaccessible passages and other possible
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ways on in the survey book. Some idea of how promising the lead is should
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always be recorded, as well as how hard it might be to get into. This will form
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the basis of the "question mark list" which will guide exploration in the
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future. That future may be as soon as another party a few hours behind, or may
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be several years later - currently each expedition generates more new question
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marks than it mops up old ones.</p>
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<p>One other aspect of surveying that is not often done whilst in the cave is
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writing the passage description. Passage descriptions complement the survey and
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may clarify things that cannot easily be shown on the map. They are also a
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very useful cross check, helping to pick up some of the blunders that are
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occasionally made. They are best written by the party that does the surveying
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(though the initial explorers should also write as good a description as they
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can), and there is perhaps a lot to be said for actually doing this on the
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surveying trip rather than later back at base camp.</p>
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<p>Surface surveys are basically similar, with the purpose of mapping the
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location of your cave, and how to get there. But there are enough differences
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and additional things to consider that they have their
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<a href="ontop.htm">own page</a>.</p>
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<hr />
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<a href="datamgt.html">Next page - 'What is cave data management?'</a>
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</body>
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</html>
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