What is "gypcrust"

Gypcrete or gypcrust is a hardened layer of soil, consisting of around 95% gypsum ( calcium sulfate). Gypcrust is an arid zone duricrust. It can also occur in a semiarid climate in a basin with internal drainage, and is initially developed in a playa as an evaporate. Gypcrete is the arid climate's equivalent to calcrete, which is a duricrust that is unable to generate in very arid climates.