lakebeds

Lakebeds are the bottom surfaces of lakes, formed by accumulated sediments carried in by inflowing water and by in-lake processes. When lakes shrink or evaporate, the lakebed can be exposed as a dry surface or develop a mineral crust. In arid and semi-arid regions, many former lakebeds persist as expansive dry lakebeds or playas, often covered with salt and clay.

Sedimentation: Lacustrine deposits accumulate through transport and deposition of silt, clay, and organic matter. In glacial and temperate lakes, varves record annual sediment cycles. In arid settings, evaporation concentrates salts, forming evaporite layers of halite, gypsum, and other minerals at or near the surface.

Structure and surface: Lakebeds vary from soft muds to hard crusts. When rainfall or runoff wets the bed, shallow lakes can re-form and rework sediments. Dry lakebeds in desert regions often have cracked surfaces, salt crusts, and surfaces that reflect mineral deposits.

Ecology and hazards: While lake waters support diverse ecosystems, dried lakebeds may host salt-tolerant microbial communities along margins. Exposed lakebeds are common sources of mineral dust that can affect air quality and climate, particularly during wind events. They also influence local albedo and heat exchange.

Human relevance and examples: Lakebeds host mineral extraction, such as salt and other evaporite minerals, and can serve as sites for infrastructure or land use changes. Global climate variability and water management have caused pronounced lake fluctuations, as seen in dryings of the Aral Sea and expansive salt flats such as Salar de Uyuni and the Bonneville Salt Flats.