Hey!

I am currently working on a tool that will generate cliffs. So far I have made the base wall of the cliff but now I want to be able to select the top edges of it so I can extrude the edge to make a sort of terrace.

I want to be able to always select the top edges of the cliff even if the height of the cliff is sloped or have a height different.
How would I do this?

Thanks!

while not answering your question DIRECTLY, if I'm faced with this problem, here's how I would get ‘around’ the problem..

Group SOP
Keep By Normals: Enable
Direction: 0,1,0
Spread Angle: tweak to whatever you need

then extrude just that group