Wiktionary
n. A thin hard layer found near the surface in soil.
Wikipedia
thumb|250px|A duricrust inselberg near Dori, Burkina Faso Duricrust is a hard layer on or near the surface of soil. Duricrusts can range in thickness from a few millimeters or centimeters to several meters.
It is a general term (not to be confused with duripan) for a zone of chemical precipitation and hardening formed at or near the surface of sedimentary bodies through pedogenic and (or) non-pedogenic processes. It is typically formed by the accumulation of soluble minerals deposited by mineral-bearing waters that move upward, downward, or laterally by capillary action, commonly assisted in arid settings by evaporation. Minerals often found in duricrust include silica, iron, calcium, and gypsum.
Duricrusts need to be formed in absolute accumulation, therefore they must have a source, transfer and precipitation. Duricrust is often studied during missions to Mars because it may help prove the planet once had more water. Duricrust was found on Mars at the Viking 2 landing site, and a similar structure, nicknamed "Snow Queen," was found under the Phoenix landing site. Phoenix's duricrust was later confirmed to be water-based.
Usage examples of "duricrust".
To make the experience seem more real, she stooped and plunged her fingers into the duricrust by her feet.
They use the last of the explosive charges to loosen the permafrost that lies beneath the friable few centimeters of duricrust, then chip out a rectangular hole and lay Dr.