ravine

Ravine is a narrow, steep-sided valley formed primarily by the erosive action of running water. It is typically smaller than a canyon and larger than a gully, though the exact size and terminology vary by region. Ravines commonly occur in hilly or mountainous terrain where streams have access to bedrock and relief is sufficient to sustain rapid downcutting.

Formation results from the long-term incision of a stream into bedrock, aided by weathering and mass wasting. Headward erosion can enlarge the ravine upstream, while episodic flows, spring thaw, or floods enhance vertical cutting. In arid regions, infrequent but intense floods can carve ravines quickly.

Morphology: Ravines usually have a V-shaped cross-section produced by downcutting and side-wall weathering. They may be straight or serpentine and often feature a narrow floor that may host a seasonal or perennial stream. The steepness of the walls depends on rock hardness, slope stability, and climate.

Ecology: The microclimate in ravines supports moisture-loving plants along the walls and floor, creating distinct habitats compared with surrounding terrain. Cool, shaded microhabitats can sustain ferns, mosses, and forest understory in temperate zones; wildlife patterns are influenced by the availability of shelter and water.

Human use and hazards: Ravines are sometimes used as drainage channels, drainage basins, or routes through terrain. They can pose hazards such as loose rock, landslides, or flash floods, especially after heavy rain. In some regions, ravines are protected as geomorphological features or part of protected landscapes.

See also: gully, canyon, gorge, valley.