How to texture a distinct section of terrain

I’m trying to create a section of terrain that i can apply a distinct texture to. I though of using the drape tool to drape a shape only the terrain and then apply the texture that way. However, when i drape the shape onto the terrain, it doesn’t let me select only that portion of terrain, it only selects the entire terrain.

Any ideas?

My guess is there’s at least one gap in the loop somewhere. Zoom in close and work your way around the edges on the terrain to look for it or them.

It might be there’s a gap in the shape you are draping, too. Can you trace an edge segment and get a face? If so, you could extrude it through the terrain and do an Intersect Face operation.