Download Soil Horizons - Environmental Geology - Lecture Slides and more Slides Earth Sciences in PDF only on Docsity! Soil Horizons • O horizon – Surface horizon – Recognizable organic matter • A horizon – First mineral horizon – Humidified organic matter • E horizon – Dominated by removals – Loss of silicate clay, iron – Resistant minerals appear to be concentrated – Lighter in color Docsity.com Soil Hozizons • B horizons – Illuvial concentration of silicate clay, iron, aluminum, carbonates, gypsum, and/or humus – Residual concentration of oxides or silicate clays – Often brightly colored – Bt—silicate clays – Bk—carbonate • C—Weathered parent material • R—Bedrock Docsity.com 12 World Soil Orders Soil Order Formative Element Description Entisol Recent Soils without pedogenic horizons Inceptisol Inception Soils with weakly differentiated horizons showing alteration of parent material Aridisol Arid Soils of arid or semi-arid climates; dry soils with pedogenic horizons; low O.M.; accumulation of bases (Ca++, Mg++,Na+, K+) Mollisol Mollify (mollis or soft) Soils with nearly black, organic-rich surface; high base supply Gelisol Gelid (very cold) Soils of cold regions; high O.M.; typically saturated; underlain by permafrost Spodosol Podzol (spodos or wood ash) Soils that have an accumulation of amorphous material (Al, O.M., Fe) in subsurface horizon; cold, wet climate Alfisol Pedalfer Gray-brown surface horizon; medium-high base supply; silicate clay accumulation in B horizon Ultisol Ultimate Low base supply; accumulation of silicate clays; typical of high rainfall and high temperature Oxisol Oxide Highly weathered; inactive clays (mainly kaolin and hydrated oxides of Fe and Al); no silicate clay accumulation Histosol Histology (tissue) Soils with a high content of organic matter; peat or muck Andisol Ando (black soil) Soils developed on volcanic rocks; dark color due to Fe-rich volcanics not organic matter Vertisol Invert Soils with a high content of shrinking or swelling clays; no horizon development Docsity.com Entisol Buried A A C SW Wisconsin Stratification and buried horizon are typical of entisols derived from fluvial material Docsity.com Entisol Central CO A (0-3”); C (3-10”); R Docsity.com AridisolDesert Pavement E & EB B Central Arizona P.M. = coalescing alluvial fans from pyroclastic rocks Docsity.com Mollisol A BA B C Eastern CO P.M. = loess The driest of this group of mollisols Docsity.com
