Sketching from memory instead of surveying.

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Sketching from memory instead of surveying.

Postby GroundquestMSA » Mar 11, 2013 8:26 pm

How do you folks feel about sketching small caves from memory or sketching at the cave, but without instruments or tape etc. ?

I just spent an enjoyable weekend caving in Greenbrier Co. WV. While heading in from a dig, my brother happened to stomp his way into a little cave. We opened up a small vertical entrance and dropped the pit to find a small amount of breakdown passage and no noticeable air. If we had found this cave back home in Ohio, we would have certainly surveyed. But in a county with 1500 caves and innumerable little dead pits, it didn't seem worth the time. After we got in we sat around and bickered about the details while coming up with this rough sketch.

click to enlarge
Image

We will likely be going to WV and KY more often, with a lot of emphasis on finding new cave. Most finds, I suspect, are going to be a lot like this one. Is there any reasonable objection to documenting these insignificant caves in a less formal manner? I enjoy surveying, but in such a rich area I would prefer to spend my time looking for better caves.
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Re: Sketching from memory instead of surveying.

Postby Scott McCrea » Mar 11, 2013 8:38 pm

I say it's better than nothing. Actually, your map looks pretty good. You could add the depth, tho. Most state surveys will accept sketch maps. TN grades their maps from a "5" meaning compass, clino, tape, etc, the full works, to "1" a sketch from memory.

It is also good to consider the audience for this map. Which it sounds like may only ever be you and your brother.
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Re: Sketching from memory instead of surveying.

Postby GroundquestMSA » Mar 11, 2013 8:48 pm

Scott McCrea wrote:It is also good to consider the audience for this map. Which it sounds like may only ever be you and your brother.


Very true.
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Re: Sketching from memory instead of surveying.

Postby Extremeophile » Mar 11, 2013 9:34 pm

GroundquestMSA wrote:How do you folks feel about sketching small caves from memory

Bad

It's a slippery slope. We have a cave here in Colorado at over a mile in length was all sketched from memory. Not really sure why they bothered.
Don't get me wrong, I think there's a use for sketch maps, but it looks like you took more time to draft it on a computer than it would have taken to do a proper survey.

I did very much enjoy the Marmot Cave map though.
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Re: Sketching from memory instead of surveying.

Postby GroundquestMSA » Mar 11, 2013 10:13 pm

It took less than 10 min. to scan the sketch and add a few bits of text. It would have taken a couple of hours or so to hike back up the hill and survey and it would have had to be done on a return trip the next day. If I have to choose between finding 3 caves and surveying them or finding 6 caves and sketching them, what's a better way to spend my weekend? I wouldn't consider sketching anything much bigger than this though, or anything that had lead/dig potential.
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Re: Sketching from memory instead of surveying.

Postby Jeff Bartlett » Mar 12, 2013 10:26 am

I agree wholeheartedly on both counts:

A. Sketching from memory with no survey is inevitably inaccurate. As a rule, don't do it.
B. No one cares when it's a 40-foot rat hole in Ohio (WV, however, deserves better).

That said, why spend 10 minutes sketching from memory when you can just spend an additional 5 minutes recording the two azimuths that would be required to orient this correctly?
"Although it pains me to say it, in this case Jeff is right. Plan accordingly." --Andy Armstrong
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Re: Sketching from memory instead of surveying.

Postby driggs » Mar 12, 2013 12:52 pm

No offense meant by asking, but are you familiar with the concept of "significant digits"? By listing the cave length of 110ft, you imply a precision of at most 10ft, which means "the cave is definitely longer than 100ft and definitely shorter than 120ft". And if I were to see that map, based on the stated length, I'd assume the cave was surveyed but merely sketched from memory.

What you're describing is a "BCRA Grade 1 survey", which is the clear way to state that no measurements were taken and the sketch is from memory. It is preferable, in my opinion, to list the BCRA survey grade on the map. If I recall correctly, the grades were formerly defined in terms of standard deviations, but were revised at some point in the not-so-distant past. Many people in the US falsely call their surveys BCRA Grade 5 when they don't actually meet that quality standard, and should more correctly be bumped down to Grade 4.

Even at 100ft of unsurveyed cave, this find is significant enough that it should be submitted to WVASS and assigned a county ID number, but I assume Greg Springer handled this for you?

Of course, most significant is your discovery of the first documented wombat in WV; I look forward to seeing the photos! :big grin:

Edit 1: I checked my 1976 edition of BCRA's Surveying Caves, and the only notable difference between published survey grade standards are that it lists 10cm distance precision for Grade 5, where the online 2002 version lists 1cm distance precision. Note that 1cm is less than half-a-tenth-a-foot, as we commonly measure in the US. So I was wrong, the BCRA grades don't appear to have at one time included standard deviations; I actually picked that nonsense up from Therion, which requires you to specify survey grade by listing the allowed standard deviation per instrument (how user-friendly!).

Edit 2: Apparently the UIS has also published a set of UIS Mapping Grades, which is news to me. But, as Bartlett pointed out to me, neither the UIS nor the BCRA grades mention backsights, they simply give precisions for reading instruments. We frequently read to a higher precision (half-degree), but allow a two-degree disagreement between fore and backsights. Where does this fall on the survey grades?! Perhaps this is veering off topic for your question...
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Re: Sketching from memory instead of surveying.

Postby GroundquestMSA » Mar 12, 2013 10:46 pm

driggs wrote:No offense meant by asking, but are you familiar with the concept of "significant digits"?


I understand the concept, but didn't really view it as a big issue. I didn't mean to imply anything except that that 110' was my best guess, which it is. It could be anywhere from 80' to 150' I suppose, depending on how you survey. The point is only to give a good idea of the size of the hole. What length would you suggest I claim? 100' ? I'm not extremely familiar with survey grades, would the majority of cavers understand what I meant if I put BRCA grade1 on the map?

driggs wrote:Even at 100ft of unsurveyed cave, this find is significant enough that it should be submitted to WVASS and assigned a county ID number, but I assume Greg Springer handled this for you?


We were on Greg's dig, and he suited up to drop the pit before we announced the brevity of the passage below. We both agreed that we didn't feel compelled to survey, but I'm sure he will submit it.

driggs wrote:Of course, most significant is your discovery of the first documented wombat in WV; I look forward to seeing the photos!


That name was the result of hearing several hours of constant puns issue forth from Dr. Springer and Ed Saugstad, and refers to the lone flying mammal observed in the cave.
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Re: Sketching from memory instead of surveying.

Postby GroundquestMSA » Mar 12, 2013 11:10 pm

Jeff Bartlett wrote:I agree wholeheartedly on both counts:

A. Sketching from memory with no survey is inevitably inaccurate. As a rule, don't do it.
B. No one cares when it's a 40-foot rat hole in Ohio (WV, however, deserves better).

That said, why spend 10 minutes sketching from memory when you can just spend an additional 5 minutes recording the two azimuths that would be required to orient this correctly?


I'm not sure who or what you're agreeing with, but of course sketching with no survey is inaccurate. That's the whole point of this topic, really. When is it ok to be inaccurate? I could sketch whatever shapes I wanted on that map, and call it a Grade Blah Blah Blah and no one would ever know the difference as long as it was a dead little pit in the middle of cave country. If I've provided a reasonably accurate description of what's in that hole, what more is needed? The same thing could be accomplished with a text description, but it's more fun and more inuitive to draw a picture.

If I took two azimuths, and no other measurements, that would satisfy you? I would personally prefer to do a proper survey if I'm going to carry survey equipment. As said before, a proper survey would have required a return trip and a lot more than 10 or 15 min. I can make this sketch riding in the car or sitting by the fire listening to cavers argue about the ethical objections to enlarging the Devil's Pinch.
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Re: Sketching from memory instead of surveying.

Postby trogman » Mar 13, 2013 7:06 am

My opinion is that a sketch map is much better than no map at all. And that is what the majority of ridgewalkers turn in-no map. Our state survey files director here in AL told me unequivocally that he prefers a sketch map to no map. The main purpose for a map of small and short caves is so that the cave can be recognized and distinguished from others in the area. For larger and longer caves, a map serves to guide explorers and help them find their way through the cave.
As far as measurements, I almost always carry a laser distance measuring tool when I ridgewalk, so my length numbers are generally fairly accurate. When I do a sketch map, I will approximate the azimuths, and if the cave turns out to be more substantial, I will make a return trip and do a formal survey. Yes, that *might* be a slippery slope, but I don't believe it is. The cutoff for me is at about 150' of passage, but that all depends on how long the hike is, or if there are other caves in the area needing surveyed as well.
I suppose I could carry all my survey gear on every ridgewalk, but as it is I am trying to go as light as possible, and every little bit adds up.

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Re: Sketching from memory instead of surveying.

Postby Chads93GT » Mar 13, 2013 9:24 am

Here in Missouri we don't "grade" surveys or maps. We just do it. I don't see the point in putting the grade that someone arbitrarily came up with. As if you need to say "my map is better than yours because I did x y and z.
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Re: Sketching from memory instead of surveying.

Postby Bumbalawski » Mar 13, 2013 10:25 am

Any map, sketch by memory or survey is a plus. If the cave is simply "viewed", it is subject to "rediscovery" over and over which adds to confusion. Some caves that we have found over the years may have been "rediscoveries". At least with a sketch, rough sizes, directions and depths are known. "Rough knowns" are always better than total "unknowns". The sketch should always be recorded in a data bank where it can be viewed by responsible other cavers for future reference. We have one cave, New Years Cave in Bedford County, Pa., that has never been surveyed, just very rough sketched. The upper portion has filled in with mud and we have made several attempts to reopen it to no avail. Fortunately we have that sketch and this cave needs reopened. Perhaps down the road, a young group of aspiring cavers will undertake the dig. They will greatly appreciate the sketch.

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Re: Sketching from memory instead of surveying.

Postby driggs » Mar 13, 2013 1:55 pm

Chads93GT wrote:Here in Missouri we don't "grade" surveys or maps. We just do it. I don't see the point in putting the grade that someone arbitrarily came up with. As if you need to say "my map is better than yours because I did x y and z.


Yes, that is absolutely the reason that I survey my caves to BCRA Grade 5, so I can puff my chest out at the grotto meeting and say that my superstar crew is able to read all the small numbers on the instruments while your neanderthal survey team didn't achieve an expected 2% error rate.

Of course, perhaps in Missouri, you guys don't need to calculate the remaining vertical extent from the known bottom of a cave to its resurgence. Perhaps you never attempt to connect two complicated caves by aligning potential tiers and morphological development paths. Perhaps you don't have geological controls on a region where a precise cave survey is the only way to map stratigraphy and structure. Perhaps you don't give landowners coordinates and depths where they should drill a well for water. Perhaps you can assume that if a map looks good, there's no need for a modern exhaustive and systematic survey that could turn up additional passage.

Or... perhaps you just don't know what you're talking about. :boxing:
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Re: Sketching from memory instead of surveying.

Postby Chads93GT » Mar 13, 2013 4:57 pm

You sure do assume a lot about me David. The Neanderthal comment was rather funny though. We still don't grade maps in Missouri. ;)
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Re: Sketching from memory instead of surveying.

Postby GroundquestMSA » Mar 13, 2013 5:47 pm

Trogman - It sounds like you and I have pretty much identical viewpoints on this matter.

Don - If I ever do some caving in PA, that sounds like the project for me. I like digging. Is it a large scale dig? PM me some details if you want.

The rest of you lads can feel free to squabble about survey grades if you want, but you aren't giving me anything to think about. I'm not "calculating the remaining vertical extent from the known bottom of a cave to its resurgence, attempting to connect two complicated caves by aligning potential tiers and morphological development paths, concerned with stratigraphy and structure, where landowners should drill a well for water, or finding additional passage," in this case. If any of those things were a consideration, I would survey, and while I don't know what grade I'm capable of producing or if I would announce the grade on the map, I would do the best I could and feel good about it.
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