4096x4096 2 metres per pixel. When imported the heightmap as full range it broke immediate. So reduced max range, smoothed with coast effect in terrain editor, and then gave a smooth in terrain editor. THat worked 90% as a fix but as soon as went round the map fixing smooth points on near verticle rock faces the breaking issue started again. I would of liked to have the mountain ranges even more dynamic as original heightmap gave nice hard edges but not a big fan of the smmothed out version. ANyfix help would be appreciated bud; Can send you the map if you want a play as going to be released to forum community anyway.