Soil horizon letter designations

Base symbols for surface horizons

O organic horizon containing litter and decomposed organic matter

A mineral horizon darkened by humus accumulation

E mineral horizon lighter in colour than an A or O horizon and depleted in clay minerals

AB or EB transitional horizon more like A or E than B

BA or BE transitional horizon more like B than A or E

B accumulated clay and humus below the A or E horizon

BC or CB transitional horizon from B to C

C unconsolidated earth material below the A or B horizon

R consolidated rock

Suffixes added for special features of horizons

a highly decomposed organic matter

b buried horizon

c concretions or hard nodules (iron, aluminum, manganese, or titanium)

e organic matter of intermediate decomposition

f frozen soil

g gray colour with strong mottling and poor drainage

h accumulation of organic matter

i slightly decomposed organic matter

k accumulation of carbonate

m cementation or induration

n accumulation of sodium

o accumulation of oxides of iron and aluminum

p plowing or other anthropogenic disturbance

q accumulation of silica

r weathered or soft bedrock

s accumulation of metal oxides and organic matter

t accumulation of clay

v plinthite (hard, iron-enriched subsoil material)

w development of colour or structure

x fragipan character (high-density, brittle)

y accumulation of gypsum

z accumulation of salts