Spain's age-old blending and maturation system, used to maintain quality and style consistency in some fortified wines. It's used most notably for Spain's sherry although producers of such wines in other countries have also established soleras. The solera system is based on the maturity levels of several wines, ranging in tiers from the oldest to the most recently produced. It consists of drawing off one-quarter to one-third of the oldest wine for bottling. The wine that was drawn off is replaced with wine from the next oldest tier, which is replaced with a younger wine from the next level, and so on up through the levels of the solera. With this process, the old wines infuse the younger ones with character, while the youngsters endow their older counterparts with nutrients, which, in fino-style sherries, gives the flor something to live on. A solera is generally pictured as tiers of wine casks stacked on top of each other, the oldest wines being the bottom level, the next oldest on the tier above that, and on up, with the youngest wine at the top. In actuality, however, the various age levels or scales (escalas) of wine may be kept in separate bodegas (storage areas). The oldest wines in a solera depend on when it was established; some are 40 to 50 years old.