Playa wetlands are generally lined by clay soils, with more than 50% clay composition in most soil and more than 80% in the center of a playa wetland. The high clay content reduces permeability and enhances the water holding capacity. The geologic origin of playas has been the subject of much debate. Some of the early theories suggested that buffalo and other large extinct mammal created wallows in the prairies and created playa wetlands. Others have indicated that meteorites may have impacted at the site of each playa and caused the formation of playa wetlands.

Several scientists have concluded that carbonates in the soil start to dissolve wherever a little depression is formed and water starts to pool. The water carries organic matter from the wetland vegetation below the soil surface. The organic matter undergoes a chemical transformation and releases carbon dioxide which mixes with the water and creates carbonic acid. This carbonic acid dissolves the carbonates and expands the depth and width of the basin to form a playa wetland. This process continues over time as plants continue to grow, die, and decay.

Wind has also been implicated in the formation and maintenance of playas. Under this scenario, wherever a small pool of water starts to form and then dissipates before vegetation has a chance to vegetate the site, will be subject to wind erosion. The loose soil is blown away increasing the depth and width of the playa wetland.

The most readily accepted idea on playa wetland formation is that it is a combination of the above described processes. The influence of each factor is more or less important depending upon the location of the playa wetland. Regardless of how they were formed, they are an important part of the landscape of the Southern Great Plains.