Loess

A fine-grained, unstratified, wind-deposited sediment dominated by silt-sized particles (typically 20–50 μm), characteristically buff or yellow in colour and capable of standing in near-vertical cliffs due to its internal cohesion from calcite cement. Large loess deposits include the Chinese Loess Plateau and parts of the North American Great Plains. Loess deposits produce highly fertile soils (luvisols/mollisols); the fertile plains of northern China's Yellow River (Huang He) derive their colour and agricultural productivity from loess.