There are a number of terms used to describe various typical landforms, which are encountered in map reading and land navigation.All these landforms are a combination of uniform, concave and convex slopes, and selected terms relating to them as follows.
- Ridge: A ridge occurs where two slopes are inclined upwards to each other to form a long narrow hilltop. Ridges are watersheds.
- Valley: A valley is the low grond between two ridges and usually has ariver or stream flowing along its lowest line of the floor.
- Spur: A spur is a projection or salient of higher ground from ridges into a valley. Successions of spurs may occur alternately on opposite sides of the valley.
- Re-Entrant: A re-entrant is the low ground between two spurs. The head of a re-entrant can be quite steep also near the bottom can be quite marshy.