Loam (clay) is a mixture of sand (particle size > 63μm), silt (particle size > 2 μm) and clay (particle size < 2μm). It is formed either by weathering of solid or loose rocks or by the unsorted deposition of the above mentioned components. Mountain loam, slope loam, glacial loam (glacier), loess loam (loess) and meadow loam (from river deposits) are differentiated depending on their origin. Loam/clay is widespread, readily available and one of the oldest building materials of mankind.