Terrain Geometry Brush?

Tried looking how to do this but failing miserably, anyone know how to do this ? …

Have you looked into Foliage Tool | Unreal Engine Documentation
Geometry Brush Actors | Unreal Engine Documentation

I did have a look but not sure what I’m looking for. These work with the terrain ?

If your wondering the texture for the terrain is a landscape material you would have to set the different textures so you get the rock look when it becomes a slope, as for the tools the road is the spline tool https://docs.unrealengine.com/latest/INT/Engine/Landscape/Editing/Splines/index.html Hope that helps some what.