How would I go about detecting cliffs using raycasting?

The question is the same as the title. I’m trying to replicate hay bail jumping from AC and I need a way to detect cliffs using ray-casting.

The longer a ray’s path, the more processing it requires. So what I would do is fill in the cliffs with an invisible part, so that the ray doesn’t have to travel very far. Also if it hits that part, then you know it’s a cliff. This trick is also used in games outside of roblox.