This one's simple; I am creating a wilderness map for a TT one-shot and the details of the map see a swampy bog in on portion of a valley running between the mountains, and a canyon going through the center. I keep wondering why the swamp doesn't drain into the canyon. Obviously I can make up some excuse but I don't much want to build this map on contrivances. There's already a lot of suspension of disbelief going on with portions of this map and I want to cut some of the fat off. I've researched high-altitude wetlands, but they don't seem to satisfy my cravings.
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$\begingroup$ laketiticaca.com $\endgroup$– jsotolaFeb 17 at 0:55
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Forgive my crude art... But your topography includes a dense rocky area that surrounds both canyon and swamp.
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1$\begingroup$ The swamp in the above illustration could occur in a cirque -- a bowl-shaped depression scraped out at the head of a glacier (another of which likely also originally carved your canyon). $\endgroup$ Feb 16 at 19:03
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1$\begingroup$ @Quinn I got the idea from an episode of Bear Grylls wilderness survival show where he explored a marshy area (I think in the Scottish Highlands), with quicksand even, that was surrounded by mountains and deep valleys. So even of its not common, its at least possible(?). $\endgroup$– LenFeb 16 at 19:08
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1$\begingroup$ That's perfect. The setting I'm rolling with is heavily glaciatic. Thanks! $\endgroup$– QuinnFeb 16 at 19:18
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1$\begingroup$ @Quinn Marshy areas and bogs on hills are common in the Scottish Highlands and in Lapland. In general, a marsh can form wherever there's sufficient rainfall and a layer of dense soil (like clay) that doesn't allow water to drain. $\endgroup$ Feb 16 at 20:21
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2$\begingroup$ @Quinn anecdotally: on Svalbard in the summers when I lived there, there would often be swampy parts on the tops of the plateaus where the glacier was melting (though fairly limited in size). Not too far off would then be massive cliffs. So, one more instance of this in real life $\endgroup$ Feb 17 at 2:07
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In North America, there's a species called a "beaver" -- which, as part of its lifestyle, dams streams with chaotic piles of limbs and brush coated with mud, and then builds lodges with underwater entrances in the same construction style in the ponds formed behind the dams.
These ponds, over time, will silt in and change to marshy land, the silt loosely anchored by water plants like bulrushes and similar.
When the water in the pond gets too shallow, the beavers build another dam, either above or below the old one (usually above) -- and over a period of decades a colony will transform a swift mountain stream into a winding "threaded" stream passing through a series of progressively less marshy meadows.
To have your marsh(es) alongside a canyon, the beavers would need to build their dam near a waterfall that drops into the canyon; then over some time, make additional dams upstream of the first; you'll then have a marsh just above a waterfall which is formed by the spillage over the dam (which keeps the marshy moisture from draining completely). Two such dams across the canyon from each other would give what you describe.
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$\begingroup$ I think I do actually have an in-world analogue to that which might make this work. I appreciate the help. $\endgroup$– QuinnFeb 16 at 18:58