English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Open

Presents the pdf analysis as premium feature

PDF Analysis

Insights

Presents the summarisation as premium feature

Summarisation

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

The fine silt (2 5 mm) and fine clay (<0.1 mm) fractions from four acid soils developed from moraines of increasing age (80, 400, 3,000 and 6,500 years old) in Switzerland, were studied by X-ray diffraction and chemical analyses. The soil parent material is homogeneous at the four sites and the soils can be considered as forming a chronosequence of soil development leading to the formation of Podzols. Mineralogical evolution of silt-sized phyllosilicates and fine clay fractions follows different pathways according to their composition and the soil horizon in which they are located. Dioctahedral and trioctahedral minerals in the soil parent material were both weathered in the Bw and Bs horizons but the trioctahedral phase more strongly and faster than the dioctahedral one. Weathering products are mica-vermiculite mixed-layers, vermiculite and finally gibbsite and Fe oxy-hydroxides. Weathering of the trioctahedral fraction was faster in the eluvial A or E horizons than in the B horizons, being almost complete after 3,000 years of soil development. Appreciable weathering of the dioctahedral fraction occurs only in the eluvial horizons leading to the formation of mica-smectite mixed-layers and smectite. Although smectite has been reported in the E horizon of Podzols in different environments, the significant finding in this work is the presence of this mineral in soils developed from the same parent material. This supports the fact that smectite is the endproduct of mica alteration in strongly leached and acidified E horizons of Podzols. The rate of clay formation in soils from temperate areas is of great interest in order to address the problem of soil resilience. This rate is required to study the possible effects of acid deposition on soils, the elemental cycling and retention and loss of nutrients in forest ecosystems. The rate of weathering and the sorption properties of weathered products also strongly influence the chemistry of surface and subsurface waters. Studies of weathering and clay formation rates require specific conditions to minimize the effect of soil-forming factors other than time (Jenny, 1941, 1980). Materials with identical characteristics exposed to weathering within various timespans must be selected in small areas to ensure that they were submitted to the same climatic events. Numerous weathering rate studies have been performed on volcanic ash deposits, which are generally well dated (Lowe, 1986), but there are fewer studies on glacial materials (Protz et al., 1984; Ugolini, 1986). We studied clay formation in soils developed from moraine bodies of increasing age which were deposited in a small valley of the Mont-Blanc area (Val d’Arpette, Switzerland) by a glacier which progressively retreated during the postand late-

Clay Formation and Podzol Development from Postglacial Moraines in Switzerland