During the Civil War the soldiers of both sides had sometimes to cross the Appalachians.
Pioneers needed to cross the Appalachian mountain range in order to get to Kentucky and Tennessee. They used the Cumberland Gap, a path through the mountain range, to do so.
The Alps.
You cross the Andes.
Caucasus mountain range.
Cascades
The pioneers crossed the Sierra Nevada mountain range to enter California on their journey westward.
The Sierra Nevada mountain range.
The Alps.
The Ural mountain range separates Europe from Asia. This range is difficult to cross and has been a natural barrier for centuries.
I think it is MOSSIF as i have done a cross word where the part of a mountain range is MOSS_F so perhaps that is it? x
Rocky Mountains
Your moms breast! :D