Cliffcrawling I: The Crimson Canyons

In the course of exploring vertical spaces, such as the rugged and crumbling cliffs of some pristine shoreline, the steep walls of a canyon cut deep into the crust of a dying planet, or the dismal depths of a chimney that leads down, down past any realm or region known to mortal man...there are obstacles to overcome, hazards to negotiate and myriads of things that might be encountered.

Cliffcrawling: The Crimson Canyons

1. The stone in this area is deceptively brittle and prone to collapsing in huge sheets. When driving spikes into or attempting to climb this stuff, there is a base 30% chance a section (1d10' wide) will collapse, sliding down in a noisy rockslide. The debris will get smaller as it tumbles and caroms off of the cliff face, and will trigger an avalanche on a roll of '1' on a d20.
2. Small split: A section of the rockface approximately (1d4) feet across breaks off from the main mass and simply falls away from everyone.
3. The wind picks up substantially. Unprotected climbers suffer a -1 penalty to their DEX scores for every half hour spent out in this unrelenting cold.
4. Niche: You've discovered a small pocket in the rockface that appears to be a small, naturally-formed cave. There is a 30% chance of the outer lip collapsing under any significant weight. The niche goes back (1d20) feet, and slants downward at a (1d30) degree angle. There is stagnant water at the bottom (20% chance of minor lair). This space floods whenever there is significant rainfall.
5. Sleet scours the upper reaches of this area. Anyone caught out in the sleet takes 1d4 damage from slipping, scraping and cold (Save for half). Anyone below the level of the sleet gets cold rain instead. Roll a DEX check/Save or lose footing or grip.
6. Split: A section of rock approximately (1d10) feet across splits off from the main mass and falls to the bottom of the canyon. It will miss everyone unless someone rolls a natural '1' on a d20. Then it will do 3d4 damage (Save for half) as it grazes whomever is in its path.
7. Dense section: The rock in a (1d20) foot area is extra dense and difficult to drive spikes into or to find any usable handholds.
8. Chalky: This section is weak, chalk-like and ultra-easy to crumble into dust with a light touch. No spikes will catch in this stuff and while you can scoop out bunches of it, no reliable handholds can be made without taking three times the usual time and effort (and they still have a base 30% chance to fail anyhow).
9. Loose rocks: (3d6) rocks up to the size of a human head break loose and roll down the rockface. If any of them hit a climber they do 1d8 damage or the climber can lose their grip instead.
10. There is an icy patch just beneath the rock here. It could be some sort of freak chimney structure or another kind of pocket, perhaps even a micro-glacier.
11. Cave: This opening goes back (1d100) feet, but is only (1d4) feet wide at its widest. There is a 20% chance of this being a lair or den, and an additional 30% chance that it connects in the back with another passage.
12. A narrow, vent-like horizontal crevice leads back into a larger space that is being used as a nest for (10d100) bats or some similar small creatures. They swarm out at dusk and there is a goodly amount of guano back inside this space that will collapse into a crumbly mess of dusty loose material; literally an avalanche of guano.
13. Big split: A section of rock (5d10) feet across breaks free and falls away from the rockface. Anyone struck takes 5d6 damage (Save for half). The heavy impact of this mass of falling stone will have a 40% chance to cause secondary avalanches or rockfalls.
14. Nest: Eagles, Vultures or Harpies have made a nest here. 50% chance to be abandoned.
15. Ledge: A narrow section of the rockface collapses inwards, forming a rough ledge. There's a 20% chance of a small aperture or passage being spotted.
16. Slanting Shaft: A constricted, slanting gap in the rock goes back at least (4d100) feet at an angle of (2d20) degrees. It is (1d4) feet wide by (1d4) feet high and varies in both dimensions (re-roll) every 20 feet.
17. Rockfall: Loose rocks come tumbling down from above. Anyone caught within their area of effect must Save or take 2d4 damage. It seems minor. But there is a 20% chance of a second, follow-up rockfall in 2d10 minutes, and it is at least double the size of the previous one.
18. Weather goes sour: The winds pick up, clouds move in and things start to get dangerously wet from condensation and mist. This is not a short little squall, but a soon to be full out thunderstorm that'll last for the next 3d4 hours. Best to seek cover. Now.
19. That outcropping is not quite what it seems. Now that you've gotten closer, you can see definite signs of what might be ruins from some sort of artificial construction; but who or what would ever build anything this remote? How did they do it?
20. The rock gives way, revealing a small niche filled with Strange Ovum.