cartography ? - expressing a slope over breakdown

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cartography ? - expressing a slope over breakdown

Postby Jeff Bartlett » Aug 28, 2007 6:59 pm

i'm working on a map of a very flat cave.

one of the few slopes in the portion we've surveyed so far is definitely a slope worth expressing on the map, but it also happens to be completely covered with flat, slabby breakdown. passage height is roughly 2', slightly lower in the middle.

besides putting a vertical deviation figure at the top and bottom, how on earth do i express this cartographically? i've tried drawing a large / exaggerated slope symbol, and i've tried drawing "contour lines" made up of small slope symbols using the caves.com illustrator brushes, but anything i do looks like crap because i'm putting it on top of breakdown.

any suggestions? should i be using some kind of stroke effect to "dodge" the area around the slope line so it stands out? if anyone has examples to offer it would be great.

(i want to be true to the nature of the cave as much as possible - in this particular section there is a choice of short paths, one a low slab belly crawl and one a more comfy hands & knees crawl that just happens to be accompanied by a foot or so of water.)
"Although it pains me to say it, in this case Jeff is right. Plan accordingly." --Andy Armstrong
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Postby SofaKingCool » Aug 28, 2007 7:13 pm

Cross sections and profiles work well.
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Postby George Dasher » Aug 29, 2007 9:26 am

You've got to sacrifice some of the breakdown detail to show the slope symbols, or leave the slope symbols out all together. The problem is that you can't show both symbols.

But another option is to show the breakdown on the inside of the passage, and then use a NSS' measured slope symbol on the outside of the passage.

The measured slope symbol isn't the same as the slope symbol used inside the passage. The measured slope symbol is a horizontal line with the measured slope angle (with the degrees symbol) written above it, and a single-sided arrow pointing downslope.

There's some NSS Cave Map Symbols shown here:

http://forums.caves.org/viewtopic.php?t=2515
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Postby Spike » Aug 29, 2007 9:31 am

You could layer and shade the breakdown to give depth to the downslope side. It could look something like this.
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Postby Dan Lamping » Sep 1, 2007 12:25 pm

The example Spike posted shows two of the conventional approaches taken here in Missouri. Both the stacked, shaded breakdown as well as small slope symbols on a large piece of breakdown. The scale your drafting at and passage dimensions will likely dictate how you'll express it. As also stated, including the breakdown in a cross section and showing the slope in the plan would also work. For me it always comes down to deciding what symbols best express the nature of the cave without cluttering the map to the point that it's difficult to interpret.
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