Is a river canyon realistic here? Why or why not?

[eepjr24]

The presence of magic (especially advanced magic) in a mining zone is a horrifying thought. Gangs of unreinforced humans can do all manner of damage in a fairly short time. Now add in something like a lone wizard who can summon an earth elemental and you have the potential for hundreds of years of work to be compressed to a couple of weeks. Imagine that wizard getting the summoning not quite right one day and pulling in vermin the equivalent of rats that like to eat tasty and valuable ores. For the D&D minded, something like a decanter of endless water is the equivalent of the strongest monitor ever devised for alluvial mining: it never runs out of water, and it doesn't need infrastructure to do its damage. The most prized and feared thing, of course, would be the hundred meter long slug that digests rock to eat the sulfide ores and leaves a trail of oxidized metal chunks in a slimy, reeking trail behind it.

You are hitting on some of the major points in the story. =) Magic is powerful, but has costs. This will be Hero system game, not D&D, but the idea's are similar enough for many purposes here. Many people have some magic, but very few people have powerful magic. Also, magic follows more closely to physics than in D&D, so things don't get created from thin air, they have to come from somewhere or pay a very high energy cost for energy to matter. This has led the Vrians (southern people) to magically altering creatures to mine, act as guards, etc. Humans who fall onto hard times are magically indentured ala 1700's England. This practice was legal but better regulated on mainland Vria.

Summoning creatures requires a contest of wills to get them to do what you want. For minor elemental constructs it's not a big deal, but something powerful like a full fledged earth elemental can be challenging even for powerful casters. And the contest of wills repeats periodically. The longer you force the being to serve the more likely it is to be hostile if it wins the contest of wills. This keeps the world from being overrun with elementals, since mages who call them too often are culled by their own creations.

Anyway, back to the canyon. =)

It seems like rapid uplift (by this I would think of something like a few centimeters per year?) combined with hard native rock (silver is commonly found in association with quartz and quartz granites) would tend toward a more vertical canyon wall? Given the rain and snowfall driving the water I would think the resulting river would be fast but vary in width / depth according to season, so during rainy season or during the snowmelt it would be a deadly torrent with no perceptible banks and other times it would be a fast but potentially crossable river with stone or small sand banks and possibly even some protruding rocks and the like.

Thanks for the ideas and discussion, this has helped a lot with my idea formation. New WIP image here.

- E

[waldronate]

A moderately recent glaciation event in hard rock would give you steep walls down to a fairly low level. For a river eroding heavily, the river would be anastamosing (lots of little channels braiding back and forth) during the dry season and probably fill the valley wall-to-wall during the melt. Pulling gold from the river sediments during the dry season might be a thing.