Tinaja is a term used in the American Southwest for water pockets formed in bedrock

Bedrock

In stratigraphy, bedrock is the native consolidated rock underlying the surface of a terrestrial planet, usually the Earth. Above the bedrock is usually an area of broken and weathered unconsolidated rock in the basal subsoil...

 depressions that occur below waterfalls or are carved out by spring flow or seepage . Tinajas are important sources of surface water storage in these arid

Arid

A region is said to be arid when it is characterized by a severe lack of available water, to the extent of hindering or even preventing the growth and development of plant and animal life...

environments . These relatively rare landforms are important ecologically because they support unique plant communities and provide important services to terrestrial wildlife .