High Quality Content by WIKIPEDIA articles! An albeluvisol in the FAO World Reference Base for Soil Resources is a soil with a thin, dark surface horizon on a bleached subsurface horizon (an albic horizon) that tongues into a clay illuviation (Bt) horizon. The Bt horizon has an irregular or broken upper boundary resulting from the tonguing of bleached soil material into the illuviation horizon. Albeluvisols correlate with Glossaqualfs, Glossocryalfs and Glossudalfs in the USDA soil taxonomy.