Glossic Horizon - Soil Geography of the USA: A Diagnostic-Horizon Approach - page 170

Fig. 16.3 Broad occurrence of soils with a glossic horizon in environmental tension zones
16.5 Soil-Forming Factors and the Development
of Glossic Soils
It is generally thought that glossic soils form as a result of a change in climate and
vegetation, whereby there is a blockage of pores from lessivage that leads to a
degradation of the upper argillic horizon (Table 16.3 ). Agricultural drainage may
also contribute to degradation of the argillic horizon (Cornu et al. 2007 ; Montagne
et al. 2007 , 2008 ). Lithologic discontinuities may affect water movement, leading
to the formation of bisequal soils with a spodic profile over an argillic profile
(Bockheim 2003 ). Podzolization, possibly initiated by a change in climate and
vegetation, degrades the argillic horizon. “Albeluvic tongues” may form in 4,600-
6,200 yr (Sauer et al. 2009 ).
16.6 Genesis of the Glossic Horizon
The dominant processes leading to the development of the glossic horizon are
argilluviation that blocks pores in the upper Bt horizon, podzolization that yields
an E' horizon within the upper argillic, ferrallitization that leads to a tonguing of
Fe-rich material, and possibly gleization from water being held at a lithologic
discontinuity. Climate and vegetation change may be the ultimate drivers of the