Pothole (landform)

Potholes, also known as caldrons, cisterns, ephemeral pools, tanks, tinajas, waterpockets, and weathering pits, are holes that were eroded away in bedrock. They are most commonly found in desert environments such as the Colorado Plateau. A few well known potholes are found in Canyonlands National Park, Capitol Reef National Park, and Moab. The Prairie Pothole Region is an area of the northern Great Plains that contains thousands of shallow wetlands known as potholes.

Potholes form on flat surfaces causing them to not have any active draining, for instance there are no streams draining the potholes. They normally form on sandstone surfaces, but can be found on other rock types such as granite and limestone. These rock types contain siliceous minerals. Potholes are capable of collecting water when it rains, freezing over when the weather gets cold, dry out in hotter weather, and can even contain some species of bacteria. Potholes range in size from a few centimeters to many meters in diameter. The cavities can be shallow or more than 15 meters deep, containing hundreds of liters of water.

Potholes can expand from erosion and weathering, water, wind, and permafrost, but the main activity of how potholes expand is from biological weathering. At one time the belief was that the only agents involved with the expansion of potholes were weathering. Within the potholes is a various eco-system that contains bacteria such as cyanobacteria, fungi, and algae which can be referred as biofilm. Potholes do not contain predators like fish or aquatic insects. The biofilm breaks down some of the siliceous minerals in the pothole for nutrients resulting in furthering the weathering the pothole. The organisms that live in the potholes have to tolerate rapid change in water temperature, pH, oxygen, carbon dioxide concentration, and ion concentration.

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