The Haras series represents a Bog soil, of Hydromorphic suborder and azonal order or, according to a recent modification in the soil classification, it belongs to the Histosol order. It is characterized by muck accumulation at least one meter deep and having a superficial layer modified by pedogenetical agents and intensified by plowing. This soil is a solid suspension in water, since the former fraction represents only 10 to 30% in volume. The X-rays analysis showed that the colloidal fraction after elimination of organic material contains kaolinite, some quartz and in one layer gibsite and a mineral with a mica struture. Tumirim is the name of the second series studied and classified as an intergrade of unidentified Great Soil Group of Latosol sub-order and the Red-Yellow Podzolic. The parent material is a clay sediment of Terciary origin and the profile is restrict, less than one meter deep. Clays skins is widespread in B but without an A2 horizon. The SiO2/Al2O3 ratio is 2.1 but this higher relation is explained through X-rays analysis which identified quartz in the colloidal fraction. The dominant clay material is kaolinite and in the B mineral with mica struture was determined, probably illite.