Definition: A depression caused by erosion by water or ice. Low-lying land bordered by higher ground; especially elongate, relatively large gently sloping depressions of the Earth's surface, commonly situated between two mountains or between ranges of hills or mountains, and often containing a stream with an outlet.
Definition: A montane grassland biome is a grassland biome which occurs in regions elevated above sea level and which has community structure determined by elevation-dependent environmental conditions.