Calcic and Petrocalcic Horizons - Soil Geography of the USA: A Diagnostic-Horizon Approach - page 110

Fig. 12.2 Family classes of soils with calcic and petrocalcic horizon
Half of the soils with a calcic horizon lacked any other diagnostic subsurface
horizon; however, argillic and cambic horizons existed above the calcic horizon in
24 % and 21 % of the soils, respectively, and gypsic horizon occurred below the
calcic horizon in 2.5 % of the soils. Two-thirds of the soils with a petrocalcic
horizon lacked any other diagnostic subsurface horizon; 25 % contained a cambic
horizon and 8 % had an argillic horizon.
12.4 Distribution of Soils with Calcic and Petrocalcic
Horizons
Soils with petrocalcic horizon comprise 61,090 km 2 , accounting for 0.8 % of the
total soil area of the conterminous USA (Fig. 12.3 ). Soils with calcic horizons
comprise an additional ~1 million km 2 , or approximately 13 % of the total US land
area. Soils with a petrocalcic horizon occur primarily in the western Basin and
Range province of western Texas (TX), New Mexico (NM), and Arizona (AZ),
with lesser areas in Nevada and Utah. Soils with a calcic horizon are concentrated in
the same region but are more broadly distributed. For example, an extensive area of
soils with calcic horizons occurs on glaciolacustrine sediments in eastern North
Dakota (ND) and South Dakota (SD) and western MN in southern ID.