The Ardennes (; ; also known as Ardennes Forest) is a region of extensive forests, rough terrain, rolling hills and ridges formed by the geological features of the Ardennes mountain range and the Moselle and Meuse River basins. Geologically, the range is a western extension of the Eifel and both were raised during the Givetian stage of the Devonian (419.2 ± 3.2 to about 358 million years ago) as were several other named ranges of the same greater range.