Spodosols are the predominant soil order in Michigan, USA. Spodic horizons form primarily through the translocation and immobilization of organometallic complexes rather than of imogolite. rotocatechuic acid is one of the low molecular weight phenolic compounds that may play a role in the podzolization process. The amounts of Al and Fe of spodic horizons increase with time. As fire frequency decreases the vegetative cover changes and spodic horizon development increases. Somewhat poorly drained soils tend to have the strongest developed spodic horizons. Water tables act as barriers to water percolating through soils, preventing organometallic complexes from moving deeper into the soils. Nearly all Spodosols in Michigan occur in sandy or coarse-loamy materials. The sand and silt fractions of Spodosols are dominated by quartz with smaller amounts of feldspars. Weathering is most intense in E horizons. Trioctahedral chlorite tends to weather from the clay fractions of the solum unless protected by oigano-metallic complexes in spodic horizons. Dioctahedral mica tends to weather to vermiculite in B horizons and to smectite in E horizons.