Transition from mountains to plains

[Arctangent]

I'm trying to create a map with high mountains in the background. However, I'd like most of the map to have a shallow slope or be flat (in order to maximize building area.

I'm having trouble creating a realistic-looking transition between rocky mountains and smooth plains. Any advice?

Is there an easy way to create a gradual change in height and gradual change in smoothness?

Any real-world examples of places that quickly transition between mountains and flat land?

Are there places where there's a really high mountain followed by a flat area followed by a coast?

 

[prismaticmarcus]

i think you'd be hard pressed to find a high mountain 18km from a coastline. geology doesn't really work that way. maybe think of it as a lake rather than the sea