Fech fech
Template:Short description Fech fech (Template:Langx) is a very fine powder caused by the erosion of clay-limestone terrain and it is most commonly found in deserts.[1] It consists of a surface horizon of pulverized soil with low particle cohesion[2] protected under a thin crust. Fech fech is derived from ancient lake muds or on certain argillaceous rocks and is one of the desert surfaces that produces dust.[3] It is not determinable from the surface and can therefore pose a significant transportation hazard acting as a surprise "trap" as the ground collapses beneath a vehicle, miring it in a quicksand-like substance.
Fech-fech is classified into two types:[2]
- Fech-fech that developed during the Holocene, in lake mud or fluvio-lacustrine sediments.
- Fech-fech that developed from shale.
Fech fech is common in the Qattara Depression in Egypt, making that portion of the Sahara Desert impassable by most vehicles.