sometimes Bg, & C Organic-rich soils with thick peaty horizons, that form in cool, well drained localities or low-lying, permanently waterlogged areas. The primary formation process is accumulation of peat (organic matter), meaning organic matter is produced faster than it can decompose in the soil. The leaching or formation of gley minerals (pyrite or siderite) overprinting prior soil or sedimentary features is associated with peat accumulation. Spodosol (sandy forest soil) Horizons: A, E, sometimes Bh, Bs, & C A subsurface horizon enriched with iron and aluminum oxides or organic matter is characteristic of Spodosols. Displays opaque cements that form distinctive radially cracked, concretionary rims to abundant quartz grains in thin sections. Spodosols form on hilly bedrock or low, rolling quartz-rich sediments. Found principally in humid climates in which clay and soluble salts are dissolved and washed out of the profile and most common in temperate regions. Characteristic vegetation are conifer forests and other kinds of evergreen woody vegetation that can tolerate low nutrient levels and high soil acidity. Alfisol (fertile forest soil) Horizons: A, sometimes E, Bt, sometimes Bk, & C Base-rich forested soils that have a light-colored surface horizon over a clayey subsurface horizon, rich in exchangeable cations. If paleosols contain nodules of carbonate in a horizon deep within the profile, such base saturation can be assumed. If lacking in carbonate nodules, Alfisols can be distinguished by the abundance of base rich clays or by molecular weathering ratios of alumina/bases of less than 2. These soils are not found at the poles or on high mountain tops. Ultisol (base-poor forest soil) Horizons: A, sometimes E, Bt, & C Base-poor forest soils that are similar to Alfisols at first glance. However, Ultisols are more deeply weathered of mineral nutrients. There should not be any calcareous material anywhere within an Ultisol profile and have molecular weathering ratios of alumina/bases of more than 2. Kaolinite and highly weathered aluminous minerals such as gibbsite are common in the profile. Low-base status is attributed to a long formation time. Form mostly on older parts of landscapes, such as rolling hills of bedrock, high alluvial terraces, and plateau tops. Natural vegetation consists of coniferous or hardwood forests. Oxisol (tropical deeply-weathered soil) Horizons: A, Bo, sometimes Bv, & C Deeply weathered soils with texturally uniform profiles. Dominated by kaolinitic clays or other base-poor oxides such as gibbsite or boehmite. Contains molecular weathering ratios of alumina/bases of