cornisa

Cornisa, or cornice in architectural and geomorphological contexts, is a term used to describe a projecting or shelf-like feature at the edge of a surface. In architecture, the cornice is the upper, outward-extending molding that crowns a wall, façade, or interior ceiling, often marking the transition between wall and roof or ceiling. Its function is both decorative and practical: it protects the wall from rain, hides joints and roof parapets, and provides a visual termination to the structure. Architectural cornices vary in complexity, from simple, shallow profiles to elaborate forms with dentils, modillions, and other sculptural details. They are a key element in classical orders and have been adapted across styles, from Renaissance and Baroque to Beaux-Arts and modern interpretations. Materials include stone, plaster, wood, and modern composites, with finishes tailored to climate and design.

Geologically, the term cornisa refers to a rock ledge or shelf along a cliff, formed by differential erosion and weathering. These shelves occur where harder, more resistant rock overlies softer layers, creating a stepped profile. Cornisas can be prominent in arid, coastal, or tectonically active regions and may serve as habitats for specialized plants and animals. They can influence erosion patterns and cliff stability, since undercutting of softer strata can lead to collapses.

In Spanish usage, cornisa commonly denotes the architectural cornice, while the geological sense is understood in technical contexts. The term emphasizes a projecting edge that defines a boundary and contributes to both structure and composition.