Duricrust

Part of speech: noun

Definitions

1. A solidified surface layer comprised of minerals that forms due to evaporation and can limit water infiltration in the underlying material
2. A firm crust of material at the Earth's surface, created by chemical reactions, often resulting in reduced soil permeability
3. A hardened top layer of soil that develops through mineral concentration from evaporation, affecting the movement of water beneath it

Etymology: Duricrust is a plain compound, built from two Latin-derived parts. The first, "durus", meant "hard" in Latin, and the same root gives English "durable" and "duration" through other routes. The second part is "crust", the outer layer of bread or pastry, which came into English from Old French and is ultimately from Latin "crusta", meaning a hard shell or rind. Put together, the word names a surface that has been hardened, usually by minerals such as iron or calcium carbonate that have been deposited and cemented near the ground surface, particularly in dry climates. The term is a technical coinage for a geological and soil-science concept, so it does not appear in ancient Latin with this sense; the compound simply describes the layer by its hardness and its crust-like form.