A coulee refers to a geographical formation that generally describes a deep canyon or a steep-sided valley formed by the action of flowing water. Typically found in areas with significant erosion and sedimentation, a coulee is commonly formed by the erosive forces of rivers or streams gradually carving out a channel over time. The word "coulee" originates from the French word "couler," which means "to flow" or "to move steadily."
Characterized by a U-shaped or V-shaped profile, coulees often exhibit steep walls or cliffs and are commonly found in arid or semi-arid regions. These formations can vary in size, ranging from small, narrow channels to massive and expansive canyons. They are typically associated with regions of former glaciation, volcanic activity, or areas with soft or unconsolidated rock layers that are easily eroded. The walls of coulees can be composed of various substrates, such as sand, gravel, clay, or solid rock.
Coulees play a vital role in the hydrological system by channeling water, sediments, and nutrients across the landscape. They often serve as important habitats for various flora and fauna, offering unique ecosystems and biodiversity. Additionally, coulees can hold cultural and historical significance, as they have been used as transportation routes, settlements, or defensive positions throughout human history.
