Loess

Loess is a homogeneous, typically nonstratified, porous, friable, slightly coherent, often calcareous, fine-grained, silty, pale yellow or buff, windblown (aeolian) sediment.^[1] It generally occurs as a widespread blanket deposit that covers areas of hundreds of square kilometers and tens of meters thick. Loess often stands in either steep or vertical faces.^[2] The term sometimes also refers to soils derived from such deposits. The word comes from the German Löss or Löß, and ultimately from Swiss German lösch (loose) as named by peasants and brickworkers along the Rhine Valley where this type of sediment was first recognized.

Loess is an aeolian sediment which forms by the accumulation of wind-blown silt and lesser and variable amounts of either sand or clay. Glacial loess is derived from either glacial or glacial outwash deposits, where glacial activity has ground rocks very fine (rock flour).