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In geology, a claypan is a dense, compact, slowly permeable layer in the subsoil having a much higher clay content than the overlying material, from which it is separated by a sharply defined boundary. Claypans are usually hard when dry, and plastic and sticky when wet. They limit or slow the downward movement of water through the soil.
Claypans provide homes to a variety of flora and fauna. One such species is the Dawson's Burrowing Bee, located in Australia. This species uses claypans as the sites for their underground nests, where individuals will they lay their broods post-mating.