I'm trying to write a story where the main characters discover the wreckage of a spaceship in the fields that border their town to the west. To the east, there's the end of a large mountain range.

Basically, the town's built into the side of the mountain. Does a mountain range have to be preceeded by foothills, or can a mountain range transition quickly into a relatively flat landscape? And if so, where on Earth has this happened?