You're welcome :)

I'm glad you managed to sort it out.

If you scroll down a bit on this article you will see how the very tall and very sheer white cliffs of Dover are shown on a late 19th century map. Generally speaking, the older the map, the more intricate the detail drawing.

I don't know how this is usually done in fantasy maps of this type, but I'm more familiar with how it is done in real world UK Ordnance Survey maps. They either use little bluff symbols or they use hachures - especially in slightly older maps of the mid 20th century. So your idea of a line isn't too far removed from that. I might add some small hachures to the cliff side of those lines if I were you. I made some just recently for my John Speed map of Dorchester if you want some quickly without having to draw your own. They are available here at the bottom of this blog, and were used in the John Speed map with Symbols Along:

If you find this little group of hachures too cumbersome to handle as a group (there can be issues if you want to go around rather tight corners) you can easily break them up into a set of separate symbols. It's a vector symbol, so it's perfectly editable.

Pretty good for a beginner :)

Just wait until you get into procedural texturing!

Sorry I couldn't be more help than that.

I hope you get it sorted out soon. It's a good looking map.