Wet soils occur in the arid and semiarid climates typical of central and western North America. Wet soils, and wetlands in general, are not prevalent in dry and seasonally dry climates, but their morphology and characteristics are considerably different from those in more humid climates. It is, therefore, important to understand the factors and processes involved in their distribution and formation. These wet soils and wetlands are commonly found at general groundwater discharge sites, such as flood plain edges, lacustrine plains (playas), artesian spring areas, and as a result of irrigated agriculture. Many of the wet soils in dry climates have formed under high evapotranspiration rates coupled with low effective precipitation, which concentrates salts in the soils of these wet areas. Therefore, geomorphology of water concentration, geological sources of the water and sediment, and evapo-concentration of salts are important.