In the World Reference Base for Soil Resources (WRB),[1] they belong mainly to the ferralsols, but some are plinthosols or nitisols.

Oxisols are always a red or yellowish color, due to the high concentration of iron(III) and aluminium oxides and hydroxides.

Present-day oxisols are found almost exclusively in tropical areas, in South America and Africa, almost always on highly stable continental cratons.

Characterized by a bright red color, these relict soils occur on uplands in a great semicircle around the southern rim, overlying associated gravel horizons said to have been cleared of sand by termites, in a prolonged and still on-going process of bioturbation.

This forces plants to get their nutrition from decaying litter as oxisols are quite infertile due to the lack of organic matter and the almost complete absence of soluble minerals leached by the wet and humid climate.