Criadera is the term used to refer to a group of barrels holding wine in a Sherry Solera. The barrels are also referred to as “butts”. In this case they hold 172 gallons of sherry.
So what is a Solera? Imagine a pyramid of barrels stacked on top of each other, filled with wine. Each line of barrels is given a “level” — i.e. First Criadera, Second Criadera, etc. In a Solera wine is pulled from the oldest criadera (the one that’s been filled the longest) and placed into bottles. Then the empty barrel is refilled with wine in the barrels from the second criadera, the second criadera is filled with wine from the third criadera, etc., etc. This process is repeated through the various criaderas.
Soleras can have a simple system of four criaderas, up to a more complex system of 14 criaderas.