Pedogenic Smectites in Podzols from Central Finland: An Analytical Electron Microscopy Study

Abstract
Transmission electron microscopy (TEM) including high-resolution transmission electron microscopy (HRTEM) and analytical electron microscopy (AEM) were used to study the fine clay fraction (d(001 ) values on lattice fringe images from alkylammonium-saturated samples shows that interlayer charge varies from high-charge expandable minerals (0.6–0.75 per half unit cell) in the younger soils to 0.5–0.6 per half unit cell in the oldest soils. Thus, the proportion of the components in the clay assemblage, as well as their chemistry and interlayer charge, change over time with soil evolution.