Survey symbols for dirt and shelves?

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Survey symbols for dirt and shelves?

Postby KsCaver22 » Dec 1, 2017 10:43 am

I did some searching around but cannot find anything useful. Are there official symbols for dirt and shelves?

For shelves I have been using a symbol that is a solid line with triangles drawn along the rock side. It is much like a floor step symbol except with filled-in triangles instead of tick marks.

Plain 'ol dirt is not commonly found in a cave, but I ran across some a few days ago. Some sources say that the symbol for sand can also be used for soil.

Thanks - Bill Gee
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Re: Survey symbols for dirt and shelves?

Postby GroundquestMSA » Dec 1, 2017 2:13 pm

The dirt symbol is simple dashes. I think it looks bad on paper and have tried in vain to come up with a suitable alternative. A shelf? Just use the ledge/step/pit symbol. Use these if you want your map to be most easily understood. Remember though that you can use absolutely any symbols you wish, as long as you provide a key.
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Re: Survey symbols for dirt and shelves?

Postby KsCaver22 » Dec 2, 2017 11:38 am

Hi GroundQuest -

Thanks for the suggestions. Plain straight dashes for dirt seem about as good as anything. For now I am using a Therion symbol called "debris" which is straight dashes oriented at random angles. It would be fairly easy to create a custom symbol where the dashes are straight.

The matter of shelves seems a bit more complex to me. A shelf is not either a floor step or a ceiling step. It is something in between. How, for example, do you decide which to use? If I use a floor step, then which side of the shelf is considered "lower" and therefore determines the tick mark orientation? The symbol I described in my original message is called "overhang" in Therion. I don't think that is quite accurate either, but it is something different from either floor or ceiling step. Changing its callout in the legend is trivial.

Bill Gee
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Re: Survey symbols for dirt and shelves?

Postby GroundquestMSA » Dec 2, 2017 6:21 pm

I may have misunderstood your meaning when you said shelf. I imagined a ledge, do you mean a thin protruding shelf, with empty space below and above? If so, I don't know of any established symbol. In odd situations like this I now prefer to tell the story with text or in the cross-section. Too many symbols on the plan view don't really help the viewer, so if a symbol is not going to be fairly intuitive or create a picture in the mind of the viewer, I leave it off and notate (if the feature is really noteworthy. If it isn't I just leave it off).

One other thought about dirt. Some cartographers use color to signify floor material. I don't because all of my maps are hand-drawn, but I have seen color used to excellent effect.
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Re: Survey symbols for dirt and shelves?

Postby chac » Dec 3, 2017 5:10 pm

Kscaver22,

I think GroundQuest has supplied the best answers. You can always create your own symbols as long as you include a legend of symbols for your map. There is actually a shelf symbol used by some cartographers. It looks just like the drip line symbol(s) however the base line to the perpendicular line is much shorter. Imagine a "+" symbol missing one of the four stubs. This symbol points a shorter stub "out" into the cave room/passage. The drip line symbol has a much longer base line, and the short stub points into the cave. The drip line symbol is also on the outer edge of cave passage (the entrance). If you have a karst window in a cave, there is another symbol that can be used.

The dirt, mud, clay symbol often appears as a series of dashed lines. Experiment if the symbol seems ponderous in your map. Delete a few of the dashed line components to make it more of a random pattern.

I see other cartographers using the shelf symbol now and again. I have used this same symbol sparingly before. Personally I find the symbol confusing due to the empty space it encloses in the plan view. So create a passage cross-section through your shelf symbol. This highlights the information you want to impart. Plan on and use cross-sections to your advantage.

There are many organizations that offer suggestions for official or recognized cave map symbology. The NSS, AMCS and the UIS all have lists of symbols to improve or standardize cave map cartography. I believe Therion comes with cave symbols built ino the program. Therion uses European map symbols, not that there is anything wrong with that. There are also cave clubs in Europe and Mexico that have their own list of cave cartography symbols.

There is a warren of "cave symbols" out there! Construct your cave symbol legend and have at it.

Jim
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Re: Survey symbols for dirt and shelves?

Postby KsCaver22 » Dec 4, 2017 7:30 am

Hi GroundQuest -

The shelves I am drawing in are flat, horizontal protrusions of rock. Imaging taking a 1x12 plank and bolting it to the cave wall so that you could set books on it. In this case the two shelves are along the same wall. They are a significant feature of the cave since the lower shelf hides the belly crawl that continues to half of the cave.

Hi Jim Coke -

I checked out the official UIS symbol table before making this post. It has nothing for either shelves or dirt. I have also checked the symbol tables in On Station. Since I am working on a Missouri cave, there is yet another table from the Missouri Speleological Survey (MSS). That table also does not contain either shelves or dirt.

Therion includes several symbol tables in its base set. UIS is among them. There is a symbol called "overhang", though I am not sure what it means.

Asking around to several other MSS surveyors with much more experience than I gets a basic consensus: KISS! Keep It Simple ... They advocate using either floor or ceiling step symbols for the shelves, then calling them out with a cross section and a note on the map. They also suggest using the clay symbol for dirt and calling it out with a note on the map. As one of them noted, "dirt is just one rainstorm away from being mud".

In this case, the map I am drawing is only for use by one other person. He is drawing the official map. My map is intended to help him interpret my sketches. Therefore I think I will use the overhang symbol for the shelves and call out the dirt pile with a note.

Thanks for your suggestions! This is definitely a learning experience.

Bill Gee
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Re: Survey symbols for dirt and shelves?

Postby chac » Dec 4, 2017 3:14 pm

Hi Bill,

Thanks for your thoughts.I understand what your situation is now. Why not just ask the cartographer if your choice of "shelf" symbol fits in with the general symbology legend she/he plan to use for the finished map? You could also add a symbol to the MSS list as well! I agree in that using an interrupted dashed line for mud, clay or (underwater/sump) silts symbol fits the eternal KISS program.

The UIS overhang symbol may be what you are describing as the 1"x12" bookshelf area for this section of cave. I am not sure though. Plan views for caves are what we are used to. Any cross sections and profiles you can provide for the cave are just as valuable to map as the plan view. Happy drawing! :grin:

Jim
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Re: Survey symbols for dirt and shelves?

Postby snoboy » Dec 5, 2017 9:23 pm

Would a cross section do a better job of describing the shelves?
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