I have yet to come across a good technique that shows how to make a realistic looking cliff face in a large, open area. The only techniques I can find would send my r_speeds through the roof. I need a technique that will give me a good looking cliff face for a chasm. Any help would be greatly appreciated,

Icoeph

You can use displacements for that ;)

I think he's working on the old dod seeing he's refering to his r_speeds.

If this is the case, then use alot of triangle shaped brushes, it's the only good way of doing cliffs on the hl1 engine.

If it's for source, use displacements