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GEOL/GEOG 321 Geomorphology
Soil Order Names and Their Formative Elements
Complied by Eric Davis (1998), Revisions by Steve Kite (2001, 2007)
Order Formative Element Derivation^ Mnemonicon
Entisol ent (nonsense syllable) rec ent
Inceptisol ept L. - inceptum , beginning inc ept ion
Alfisol alf (nonsense syllable) ped alf er
Spodosol od Gr. - spodos , wood ashes p od zol; od d
Alfisol alf (nonsense syllable) ped alf er
Ultisol ult L. - ultimus , last ult imate
Oxisol ox Fr. - oxide , oxide ox ide
Gelisols (^) el L. - gelare, freeze gel ifluction
Mollisol oll L. - mollis, soft m oll ify
Aridisol id L. - aridus , dry ar id
Histosol ist Gr. - histos , tissue h ist ology
Vertisol ert L. - verto , turn inv ert
Andisol and Sp. - Andes and esite
For images and summaries on the 12 orders go to: http://soils.usda.gov/technical/soil_orders/
Simplified Key to Soil Orders
If soil has: Order (rmuch over-simplified from 2006 keys)
- Soils with permafrost within 1 to 2 m of the surface - Gelisols
- Other soils with high organic content - Histosols
- Other soils with a spodic horizon - Spodosols
- Other soils that have andic soil properties in 60% or more of the soil thickness - Andisols
- Other soils with an oxic horizon within 1.5 m - Oxisols
- Other soils with more than 30% clay, slickensides and cracks when dry at 18-50 cm - Vertisols
- Other soils with a calcic, gypsic, petrocalcic, petrogypsic, natric, or salic horizon, or a duripan - Aridisols
- Other soils that have an argillic horizon but a base saturation <35% at 0.75 to 2.0 m - Ultisols
- Other soils that have a mollic epipedon - Mollisols
- Other soils that have an argillic or natric horizon or well developed fragipan - Alfisols
- Other soils that have an Cambic horizon - Inceptisols
- Other soils - Entisols
For details, Ch. 4 in Natural Resources Conservation Service, 2006, Keys to Soil Taxonomy 10th Edition, 331 p., URL: http://soils.usda.gov/technical/classification/tax_keys/keys.pdf
Suborder Names - Formative Elements and Meaning (Partly updated to 1998 Soil Taxonomy Revisions) Formative Element Derivation Mnemonicon Meaning or Connotation alb L. - albus, white alb ino Presence of albic horizon and Modified from Ando And o Andolike (Andes Mtns, JSK) aqu L. - aqua, water aqu arium Characteristics assoc. with water ar L. - arare, to plow ar able Mixed horizons arg Mod. from argillic L. - argilla, white clay arg illite An argillic horizon bor Gr. - boreas, northern bor eal Cool cry Gr. - Kryos, cold cry stal Permafrsot or cryo turbation (JSK) ferr L. - ferrum, iron ferric Presence of iron fibr L. - fibra, fiber fib rous Least decoposed stage fluv L. - fluvus, river fluv ial Floodplains fol L. - folia, leaf fol iage Mass of leaves hem Gr. - hemi, half hem isphere Intermediate decomposition hist Gr. - histos , tissue h ist ology Organic Soil hum L. - humus, earth hum us Presence of humus lept Gr. - leptos, thin lept ometer Thin horizon ochr Gr. - base of ochros, pale och er Presence of Ochric epipedon orth Gr. - orthos, true orth ophonic The common ones plagg Mod. from Ger. - Plaggen, sod Presence or a plaggen horizon psamm Gr. - psammos, sand psamm ite Sand texture rend Mod. from Rendzina rendzina Rendzina-like sapr Gr. - sapros, rotten sapr ophyte Most decomposed stage torr L. - torridus, hot and dry torr id Usually dry trop Mod. from Gr. - tropikos, of the solstice trop ical Continually warm turb dis turb ed Cryoturbation by permafrost ud L. - udus, humid ud ometer Of humid climates umbr L. - base of umbra, shade umbr ella Presence of umbric epipedon
plac Gr. - base of plax, flat stone Presence of a thin pan plagg Mod. from Ger. - Plaggen, sod Presence or a plaggen horizon plinth Gr. - plinthos, brick Presence of plinthite psamm Gr. - psammos, sand psamm ite Sand texture quartz Ger. - quarz, quartz quartz High quartz content rend Mod. from Rendzina rendzina Rendzina-like rhod Gr. - base of rhodon, rose rhod odendron Dark red colors sal L. - base of sal, salt sal ine Presence of salic horizon sider Gr. - sideros, iron sider ite Presence of free iron oxides sombr Fr. - sombre, dark somb er A dark horizon sphagno Gr. - sphagnos, bog sphagn um moss Presence of sphagnum moss sulf L. - sulfur, sulfur sulf ur Presence of sulfites torr L. - torridus, hot and dry torr id Usually dry trop Mod. from Gr. - tropikos, of the solstice trop ical Continually warm ud L. - udus, humid ud ometer Of humid climates umbr L. - base of umbra, shade umbr ella Presence of umbric epipedon ust L. - base of ustus, burnt comb ust ion Dry clim., usually hot in summer verm L. - base of vermes, worm verm iform Wormy, or mixed by animals vitr L. - vitrum, glass vitr eous Presence of glass xer Gr. - xerox, dry xer ophyte Annual dry season
Extragrade Formative Elements (Partly updated to 1998 Soil Taxonomy Revisions)
Formative Element Derivation Connotation Abruptic L. - abruptum, torn off Abrupt textural change Aeric Gr. - aerios, air Aeration Anthropic Gr. - anthropos, man Anthropic epipedon Arenic L. - arena, sand Arenic surface horizon Cumulic L. - cumulus, heap Thickened epipedon Epiaquic Gr. - epi, over, and aquic Surface wetness Glossic Gr. - glossa, tongue Tongued horizon boundaries Grossarenic L. - grossus, thick and arena, sand Grossarenic surface horizon Hydric Gr. - hydor, water Presence of water Leptic Gr. - leptos, thin Thin soil Limnic Gr. - limn, stone Limnic materials present Lithic Gr. - lithos, stone Shallow lithic contact present Pachic Gr. - pachys, thick A thick epipedon Paralithic Gr. - para, beside and lithic Shallow paralithic contact present Pergelic L. - per, throughout; gelare, freeze Permanently frozen Petrocalcic Gr. - petra, rock and calcic Petrocalcic horizon present Petroferric Gr. - petra, rock and liferrum, iron Petroferric contact present Plinthic Gr. - plinthos, brick Plinthite present Ruptic L. - ruptum, broken Intermittent horizon Superic L. - superare, to overtop Plinthite at surface
Terric L. - terra, earth Mineral substratum Thapto Gr. - thapto, buried A buried soil
Abbreviated Soil Family Mineralogy Classes (pre-1998 revision of Taxonomy)
Class Definition Determinate Size Fraction (mm)
1. Used if applicable in any textural family Carbonatic >40% carbonate whole soil < Ferritic >40% reducable Fe2O3 whole soil < Gibbsitic >40% gibbsite plus bohemite whole soil < Oxidic % ext. Fe2O3 + % gibbsite / % clay>or= 0.2 <40% whole soil < any other mineral; <90% quartz in 0.02- Serpentinitic >40% serpentine minerals whole soil < Gypsic Carbonatic with >35% gypsum whole soil < Glauconitic >40% glauconite whole soil <
- Used only in sandy or loamy textural families Micaceous >40% mica 0.02 - 20 Siliceous >90% silica minerals 0.02 - 2 Mixed None of the above group 1 or 2 families 0.02 - 2
- Used only in clayey textured families Halloysitic >50% halloysite <0. Kaolinitic >50% 1:1 clays and <10% expanding 2:1 clays <0. Montmorillonitic >50% montmorillonite <0. Illitic >50% mica (illite) <0. Vermiculitic >50% vermiculite <0. Chloritic >50% chlorite <0. Mixed None of the above mineralogical families
For Info on State Soils see http://soils.usda.gov/gallery/state_soils/
