Podsolisation is an extreme form of leaching which causes the eluviation of iron and aluminium sesquioxides.
Many podsol soils form underneath coniferous forests, the fact that pine trees are evergreen causes a very thin litter layer inhibiting the production of humus.
As a result, an acidic (pH 4.5) mor humus is produced which provides a greater amount of chelating agents.
[2] In podsolisation, chelating agents break down clay and release minerals such as iron and aluminium.
[3] The B Horizon has dark layer where minerals, organic matter and bases are being illuviated (washed in/accumulated).