dike

A dike, or dyke, is a term with two principal meanings. In civil engineering, a dike is a man-made embankment or wall designed to prevent flooding by confining high water along coasts, rivers, or around low-lying land. Dikes are typically built from earth or rock and may be faced with concrete or masonry. They often form part of a broader flood defense system that includes drainage, pumping stations, sluices, and gates to manage water levels and storm surge. The word dyke is commonly used in some regions to refer to the same structures.

In geology, a dike is a sheet of igneous rock that cuts across preexisting rock formations. Dikes form when magma intrudes into cracks and solidifies into tabular bodies that intersect surrounding strata. They are usually vertical or steeply inclined and can vary in thickness. Dikes differ from sills, which are intrusions that run parallel to layering. Dikes are common in volcanic areas and can host ore deposits or serve as indicators of past magmatic activity.

Regional spelling variations reflect different usage patterns, but both senses share a common root related to barriers or intrusions. In flood-control contexts, the integrity and maintenance of dikes are essential for protecting populations and infrastructure, while in geology, dikes help scientists interpret the history of tectonic and magmatic processes.