Origin of red‐yellow mottling in a Ferric Acrisol of southern Spain

Abstract

AbstractWe studied the spatial distribution of the amount and types of Fe oxides in a Ferric Acrisol having a red‐yellow mottled horizon. Red mottles contain hematite and goethite; yellow mottles have goethite but in amounts markedly smaller than those of the contiguous red mottles. We think that reductive dissolution caused the disappearance of the hematite and part of the goethite in the yellow mottles. This is supported by the experimental dissolution of the iron oxides of the clay fractions: hematite dissolved, on the average, at a rate twice of that of goethite.