I am slamming my head against a wall here.

I am in the process of trying to find a way to show a higher than usual mountain range, similar to the edge of a Crater, surrounding an entire landmass. The landmass is not a perfect circular shape, but more rigid with a single chain of mountains that encompass the entire outer edges of the land. The parts facing the water would be steep cliffs while the inner portions would be inclines.

I am currently playing around with multiple mapping methods, from a topography style to a possible older map style with a legend and such. I can handle everything else, but this...this one thing is driving me up a wall!