Many streams in southern Arizona are either ephemeral (they only flow a small part of the year) or intermittent (the water is disjointed during dry seasons with pools of water separated by dry stretches, often connected by underground flow). Many of those same streams are also partly or completely lined with bedrock, a solid layer of rock over which the water flows. In bedrock-lined streams, the water doesn’t soak into the ground during dry periods and instead sits on top of the rocks as shrinking pools:
Tinaja in Madera Canyon
These pools are called tinajas (tih-NAH-hahs) and are very important to many desert aquatic insects. In fact, they are often the only reason many insects survive until the rains return and flow is restored in the stream. They are absolutely full of life!
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The Dragonfly Woman 
Funny, I did not know those pools were called tinajas. I always thought tinajas were these.
I have a feeling it’s an Arizona thing and they’re not really known by that word anywhere else. It’s kinda like how Arizonans call ranch ponds cattle tanks. Everyone else in the world thinks of those corregated metal watering tanks when they hear the phrase “cattle tank” while Arizonans think of little ponds. We have to be different apparently!
texas uses tinajas and cattle tanks like arizona.
Nice! Glad to know we aren’t the only ones.