Yes of course. In the Terrain Pallete(Windows >new pallete>Terrain Pallete) you can chouse to edit the hight of the terrain.
Raise,Lower,Plateua,Noise,Smooth
You use Rise and make a big hill an mountain. Then you select the Plateua tool but make the hill around the map not all over the place, with plateua you select the botom of the hill so to say so the terrain tha tinst modifed and go to the hill(I mean hold it and go foward to the hill and just make it in a line) I hope you understand this better