Dear researcher,

I would go for reliefs. What do you think?

nic

I would use the following per Funk and Wagnalls Standard College Dictionary 1977:

Highlands - a hilly or mountainous region

'Terrain' or 'relief' covers collective changes in elevation. Because remember, if we are speaking about mountains and hills etc, we are also speaking about valleys and gullies, because these lie between the mountains and hills. 

Terrain or relief are generic terms that do not imply height.

American Geological Institute Dictionary of Geological Terms, 1976.

relief - 1. The physical configuration of a part of the earth's surface, with reference to height and slope or to irregularities of the land surface; the elevations or differences in elevation between the summits and the lowlands of a given region.

 terrain - 1. a tract or region of the earth's surface considered as a physical feature, an ecologic environment, of a site of some planned activity of man

The Concise Oxford Dictionary of Geography. 1992.

relief - The shape of the earth's surface.

terrain - An area of land, often seen in terms of its distinct relief.

Neither of these terms tell the reader that it is mountainous or hilly.

Thank You Everyone... your suggestions helped me  a lot in understanding the concepts better.