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Many soils in the western U.S.A. contain one or several carbonate-enriched zones (CEZ). Their carbonate admixture is often attributed to steady eolian influx, with intermittent leaching episodes of variable intensity leading to pedogenic enrichment at various depths. This hypothesis would require carbonate contents to decrease and depths to those horizons to increase with elevation. Here I compute correlations for the upper three CEZ of the surface soil and of up to two buried soils between elevation, carbonate content, depth to horizon, and particle-size distribution to test for elevation- dependent trends. Actually, carbonate-content decreases with elevation indicate such trends exist and can be determined with this approach. However, some significant relationship of elevation and depth to CEZ is not supported by the data. Furthermore, influence of local carbonate on CEZ in the surface soils calls for lateral translocation. Gravelly, now-buried sediments collected eolian carbonate better than finer ones, which finding implies these sediments were at the surface once and fossilized later. Altogether, the data indicate cyclical evolution: Several cycles of the formation of colluvial slope deposits with admixed carbonate-bearing loess particles were each followed by pedogenic translocation of the carbonate just to the depth of the next parent-material disconformity. Thus, disconformities are major triggers of soil-carbonate accumulation.

Palaeosols between deposits of the last two deep-lake cycles in the northern Great Basin have multiple carbonate-engulfed horizons, and compound calcic and argillic properties at depth. They are difficult to explain pedogenetically because they bifurcate in places, especially in basin centres where they are separated by sediments of a minor lake expansion of probable early Wisconsinan age. One sequence of processes can account for all phenomena: two cycles of colluviation and synchronous admixture of loess particles were each succeeded by the formation of an argillic over a calcic horizon. Carbonate enrichment resulting from the later period of soil formation affected the buried older soil. This led to welding of the two soils and the formation of a compound horizon carrying the argillic properties of the first and the calcic properties of the second pedogenic phase. Steady aeolian influx to the same soil surface, the commonly invoked mechanism, cannot explain the bifurcated palaeosols and is not needed to explain the welded ones.

Soil profiles developed on moraines of the penultimate glaciation on the Russian Plain have formed from redistributed material, mainly sand, derived from upslope. This material consists of layers, some of which also contain, or may even be dominated by, loess. The lowest layer differs little from the underlying substratum except where it covers deposits other than till; it is mainly inherited from till, but has been altered by solifluction, leading to downslope clast orientation and to a high bulk density. The overlying layers, also solifluction deposits, contain loess, the content of which increases towards the surface. Deeper profiles on flat relief, especially on one particular toeslope, are divided into at least three of these layers, the lowest of which contains a mature truncated paleosol. This buried soil, an Alfisol with clay–humus cutans, is assumed to represent the soil of the last interglacial. Above this, the illuvial horizon of the surface soil is developed. This is overlain by the uppermost layer, which is of loose consistency and rich in loess. It contains the eluvial horizon of the surface soil. On flat relief, modern pedogenesis is dominated by perched water tables resulting from differences in the bulk density of the layers. The maximum loess content in the upper layer and the wide distribution of a paleosol and an intermediate layer make these layers different from similar sequences in Central and Western Europe.

In parts of southern France, the Russian Plain, south central Turkey, the western USA and in Germany, slopes are covered by deposits (cover-beds) formed by geomorphic processes not limited to linear discharges. Often, loess material is mixed into them. Cover-beds usually form sequences of two or more distinct layers, and their distribution depends on the geomorphic, climate-driven processes of their formation. As they influence pedogenesis, they contribute to the understanding of soil properties and soil distribution. Horizon boundaries occur at depths where cover-bed properties change. Where aeolian matter is mixed in, podzolisation is buffered but depletion of clay may occur; loess-rich cover-beds may entirely decouple pedogenesis from bedrock influence. In humid areas, soil-water stagnation is often associated with varying cover-bed bulk densities, particularly upon flat relief. In semiarid areas, deep soil profiles consist of multiple layer sequences often with argillic and calcic properties within the same horizons. They reflect several cycles of cover-bed deposition and incorporation of loess, alternating with decalcification accompanied and followed by clay translocation. This led to the overprinting of buried soils by pedogenic carbonate leached from younger sediments. Synchronous sediment and/or airborne carbonate accretion and pedogenesis, which is usually invoked to explain soil profiles with several calcic horizons, cannot apply to cover-beds.

Slope deposits, which veil entire slopes or large parts of them in a rather uniform manner (cover beds), are ubiquitous in the subdued mountains of Central Europe (e.g., Kleber, 1992a ). Here, we show that successions of cover beds are not restricted to this area but occur in many other regions of rather different natural inventories, such as the European Alps, the Russian Plain, south-central Turkey, and the western USA (Great Basin and Rocky Mountains). Cover beds usually form sequences of two or more distinct layers, and their distribution depends on the geomorphic, climate-driven processes of their formation. As they influence pedogenesis, they contribute to the understanding of soil properties and soil distribution: horizon boundaries occur at depths where cover-bed properties change. The properties of the layers and of the soils developed in them are different per region: in humid areas layers free of admixed loess components, thus being solely influenced by weathered local materials, are frequent, whereas in dry regions such layers have not yet been reported. In several areas studied in this chapter, paleosols either occur within cover-bed successions or have been reallocated and incorporated into the cover beds. This provides handles to the ages of layers. The layer successions slowly change with elevation but show a drastic break at around the timberline where Holocene rather than Pleistocene periglacial slope processes gained supremacy.

The genesis of soils has been seen mostly as an autochthonistic process, that is, formation in situ . However, soil geomorphologists have recognized addition and loss of materials, for example, through eolian and colluvial processes, as a major contribution to allochthonistic soil formation. The most important characteristic of these soils is the lithological discontinuity, which separates the lower residual material from the upper allochthonic soil. The chapter deals with (1) developing a model joining the ideas of in situ formation and near-surface processes such as adding or removing material, (2) the pedogenetic processes in soils with lithological discontinuities, and (3) the effect of lithological discontinuities on physical and chemical properties of soils.

Disconformities within soil-parent materials are frequently reported from locations throughout the world, but they are rarely within the goals of systematic research. This article provides an overview of the current state of knowledge on such materials and their pedogenic relevance in Germany. It intends to encourage further discussion on stratified soils in other parts of the world. The slope deposits in Germany are divided into (1) the upper layer that is ubiquitously distributed and displays a relatively constant thickness; (2) the intermediate layer that is restricted to flat relief, to hollows, and to lee-ward facing slopes; and (3) the basal layer that is rather widespread again. Both the upper and intermediate layer contain intermixed loess, while the basal layer is free of loess. These layers were mainly formed by periglacial solifluction. Such deposits are referred to as cover-beds. The upper layer formed during the Younger Dryas within a relatively short episode. In contrast, the lower layers may be diachronous; nevertheless, they display recurring vertical sequences. This is probably due to the fact that loess-free layers usually could not deposit as long as there was loess in the environs. Thus, the last phase of surface wash, during which older loess was removed, determines the age of the lower layers. The composition of the layers differs, reflecting the varying portions of loess and of rock allocated from upslope. In twofold sequences, the cover-beds influence the formation of the soils as they provide weathered material, and as their boundaries, where properties such as texture and bulk density abruptly change, determine the soil-horizon boundaries. Some pedogenic processes are favored (oxidation, depletion of clay), or hindered (podzolization) due to the loess content of the upper layer. Even exceeding this, the dominant loess content of an intercalated intermediate layer in threefold sequences may completely decouple pedogenesis from bedrock influence. In all, soil formation is largely influenced by the constellation of cover-beds at any given site.

Quantifying post-depositional alteration of mineral soil material is complicated by the fact that many soils consist of layered parent materials with varying indigenous composition. Part of our study site in the Steigerwald Mountains of northern Bavaria was cultivated during the Middle Ages and later reforested. Soil erosion removed the upper materials, exposing a deposit to contamination from the surface, whereas nearby, the deposit remained protected by overlying layers. We compared heavy metal concentrations within that deposit across this boundary of varying protection. No significant results were obtained for Cd; however, the concentrations of Pb and Cu increase by about 100% or more where the protecting cover thins. The Pb and Cu values provide a measure of the gross post-depositional alteration of that deposit. We expect this procedure can help quantify various pedogenic alterations by comparison with essentially the same, unaltered parent material.