Pollen analysis and rates of pollen incorporation into a radiocarbon-dated palaeopodzolic soil at Haugabreen, southern Norway

Pollen analysis of the organic surface (FH) horizon of a radiocarbon-dated palaeopodzol buried beneath the 'Little Ice Age' outer moraine of Haugabreen west of the Jostedalsbrecn ice-cap, southern Norway, provided evidence for environmental change in the area between ca. 4,000 B. P. and the 13th century A. D. Radiocarbon dating of the profile, apart from providing a chronology for the changes interpreted, also allowed estimation of pollen incorporation rates into the soil which can be compared with pollen influx rates established elsewhere. Two periods of local woodland recession were identified, the first between ca. 3,300 B. P. and ca. 3,600 B. P., after the initiation of the FH horizon, and the second in the 13th century A. D. at the onset of the Little Ice Age.     

Development of pollen assemblage zones in soil profiles in southeastern England

Four soil profiles within c. 4 ha of dry heathland on lping Common, southeastern England were studied. Two were podzols, one was a buried profile from beneath a Bronze-age barrow and one was a profile buried beneath sediment in a small pond. Loss on ignition, particle size analysis, iron concentration and pollen concentration were determined and a pollen diagram prepared for each profile. It is suggested that discrete soil pollen assemblage zones arise from their incorporation by successively shallower-burrowing earthworm populations as the soils and vegetation change from mull to mor types. The implications of this mode of incorporation to the interpretation of soil pollen diagrams are discussed. A sequence of vegetation and soils for this area is suggested as follows:(1) mixed deciduous woodland of Quercus. Tilia and Corylus with a fern-rich understorey growing in a mull soil, (2) scrub woodland of Betula and Corylus with Pteridium and some Callunu, (3) Calluna heathland on podzolised soils. ¹⁴C dates obtained from podzol Bh horizons and the buried soil beneath the pond were inconclusive.     

Palynological and Radiocarbon Evidence for Deglaciation Events in the Green Bay Lobe, Wisconsin

A new and significant site of organic silty sand has been found beneath the Valders till at Valders Quarry in northeastern Wisconsin. This is now the earliest known late-glacial site associated with red till ice advances in the western Great Lakes area. Leaves of terrestrial plants washed into a small depression provide a date of 12,965 ± 200 yr B.P. (WIS-2293), which is significantly older than the Two Creeks Forest Bed (ca. 11,800 yr B.P.). Percentage and concentration pollen diagrams suggest that the site was open and distant from a closedPiceaforest. No wood orPiceaneedles have been found. This date is statistically indistinguishable from 12,550 ± 233 yr B.P., the mean of three dates for the end of inorganic varve sedimentation at Devils Lake, 160 km southwest at the terminus of the Green Bay Lobe. Assuming that the Green Bay lobe vacated its outermost moraine in the interval from 13,000 to 12,500 yr B.P., only a short time was available for retreat of the ice margin over 350 km, drainage of red sediment from Lake Superior into the Lake Michigan basin, readvance of over 250 km, retreat of at least 80 km, and advance to this site. The time for these events appears to have been too short to resolve by current radiocarbon technique. This extremely rapid collapse of the Green Bay lobe has a calibrated age of about 15,000 cal yr B.P., about that of the dramatic warming seen in the Greenland ice cores.     

Preboreal deglaciation chronology and marine limits of the Lyngen-Storfjord area, Troms, North Norway

Scattered marginal moraines in the Lyngen-Storfjord area proximally to the Tromsø-Lyngen moraine were formed by the Scandinavian ice-sheet during its retreat in the Preboreal. They correspond to ice-front positions in the main fjords and fjord-valleys where between three and four major and, in places, some minor ice-front accumulations occur. These have been correlated using the marine limits related to synchronous shorelines. Dates for the shorelines and moraines have been derived from a shoreline emergence curve based on ₁₄C dated shore levels from North Norway. Two major, and probably at least one minor, climatically induced, glacial events are indicated: the Ørnes event c. 9800–9900±150 B.P., the Skibotn event 95–9600±150 B. P., and a younger event c. 9400±250 B. P. The inner fjord-valleys were probably deglaciated by c. 9100 B. P. Final deglaciation of the innerplateau during late Preboreal or early Boreal was characterized by downwasting.     

Nitric-acid soluble fractions of 21 elements in Norwegian podzols: Factors affecting regional differences in vertical distribution

Distributions of 21 major and trace elements in HNO₃ extracts of different horizons were studied in 13 podzol profiles from the boreal forest in different parts of Norway using ICP–MS. On the basis of ratios between the HNO₃-extractable fractions in the various horizons some general trends were elucidated. Two different groups of elements concentrated in the humus layer relative to the mineral horizons were identified, one mainly associated with contributions from air pollution (As, Cd, Sb, Pb), another one with plant nutrient circulation (K, Ca, Mn and to a lesser extent Mg, Co, Ni, Rb) and some with both mechanisms (Cu, Zn, Tl). The elements most clearly enriched along with Fe in the B horizon were V, Pb, Al, and Cr in that order, Pb partly because of leaching from the polluted organic surface soil. Four soils in the far south showed a behaviour distinctly different from the rest and were treated as a separate group. Relative to the more northerly sites the surface horizons of these soils were strongly depleted in lithogenic elements (Mg, Al, K, Ca, Sc, V, Cr, Mn, Fe, Co, La) and enriched in elements typical of long-range transport of pollutants (As, Cd, Sb, Tl, Pb). Also the B horizon in the southern soils was strongly depleted in the lithogenic group elements, including Fe and the associated metals. The main reason for this difference is assumed to be the greater influence of transboundary air pollution and associated metals and stronger soil acidification in the far south of the country.     

Late quaternary vegetational change in the Kotzebue sound area, northwestern Alaska

Two sediment cores from Kaiyak and Squirrel lakes in northwestern Alaska yielded pollen records that date to ca. 39,000 and 27,000 yr B.P., respectively. Between 39,000 and 14,000 yr B.P., the vegetation around these lakes was dominated by Gramineae and Cyperaceae with some Salix and possibly Betula nana/glandulosa forming a local, shrub component of the vegetation. Betula pollen percentages increased about 14,000 yr B.P., indicating the presence of a birchdominated shrub tundra. Alnus pollen appeared at both sites between 9000 and 8000yr B.P., and Picea pollen (mostly P. mariana) arrived at Squirrel Lake about 5000 yr B.P. The current foresttundra mosaic around Squirrel Lake was established at this time, whereas shrub tundra existed near Kaiyak Lake throughout the Holocene. When compared to other pollen records from north-western North America, these cores (1) represent a meadow component of lowland. Beringian tundra between 39,000 and 14,000 yr B.P., (2) demonstrate an early Holocene arrival of Alnus in northwestern Alaska that predates most other Alnus horizons in northern Alaska or northwestern Canada, and (3) show an east-to-west migration of Picea across northern Alaska from 9000 to 5000 yr B.P.     

土垫旱耕人为土中磷的分布特征及其土壤发生学意义

本研究以我国半干旱地区的土垫旱耕人为土为对象,分析在自然土壤发生过程和人类活动影响下,不同形成阶段内土壤中总磷（TP）、速效磷（AP）、有机磷（OP）和无机磷（IP）的含量和分布特征。同时也探讨现代土壤利用方式的影响。结果表明,与半干润淋溶土层相比,堆垫层总磷、速效磷、有机磷和无机磷平均分别增加0.29,4.67,0.20和0.30倍;堆垫层段内,现代耕作层（Aup1）中各形态磷含量最高,向下至亚耕层（Aup2）迅速降低,而由亚耕层（Aup2）至埋藏耕作层（Aupb）和半干润淋溶土表层（2A）总磷和无机磷逐渐降低,反映了不同历史时期人类活动强度不同;半干润淋溶土层段内,土壤中的磷主要来自于黄土母质,其变化以受自然成土因素影响为主,总磷、速效磷、有机磷、无机磷含量较低且层间变化不大。菜地土壤中堆垫层内各形态磷的含量显著大于农田土壤。土壤利用方式对磷的影响大于堆垫厚度。各形态磷在剖面中的分布模式与磷素自身的迁移、淋失到下层的钙等因素有关,同时也受根系的吸收、人为灌溉施肥等因素影响。剖面中OP与OP/IP之间以及各形态磷与其他土壤理化性质的关系可以指示自然条件和人为影响的差异。     

The pattern of Neoglacial glacier variations in the Okstindan region of northern Norway during the last three millennia

BOREAS Griffey, N. J. & Worsley, P. 1978 03 01: The pattern of Neoglacial glacier variations in the Okstindan region of northern Norway during the last three millennia (Okstindan Research Project Report 26). Boreas, Vol. 7, pp. 1–17. Oslo. ISSN 0300–9483.
Historical, lichenometrical and stratigraphical evidence is combined to establish a provisional history of Neoglacial glacier variation in a mountainous environment approx. 66^oN. Attention is focussed on end moraine chronology. At five sites, derived organic materials have been located within end moraines and at two others in situ palaeosols occur buried beneath distal slopes. Organic rich samples from all the sites have been radiocarbon dated and the results permit the recognition of three major glacier expansion episodes, each of which contributes to the diachronous nature of the Okstindan outer Neoglacial limit. A widespread 'Little Ice Age' event with a maximum extent of probable eighteenth century age is confirmed. Limited areas of older moraine ridges peripheral to the 'Little Ice Age' maximal limit appear to date from about 3000-2500 ¹⁴C years B.P. and a younger period tentatively dated as about 1250-1000 ¹⁴C years B. P. which agrees with recent data from Engabreen in northwest Svartisen. No evidence for any extensive glacial activity after the inlandice wastage approx. 9000 ¹⁴C years B. P. and prior to 3000 ¹⁴C years B.P. was forthcoming.     

Nature and palaeoenvironmental significance of a buried soil sequence from Magilligan Foreland, Northern Ireland

Soil horizons delimit three periods of sand deposition and subsequent topographic stability at Magilligan Foreland, Co. Londonderry. All the deposits are composed of texturally and mineralogically similar material. The earliest topography is a beach ridge plain; podzols cap the ridges and peats occur in the inter-ridge depressions, together comprising a buried palaeocatena. The podzols are visually distinct but chemically and mineralogically immature. Peat and podzol genesis probably began between 3,000 and 2,500 years B.P., and were terminated between c . 1,100 years B.P. and c . 600 years B.P. by burial under an extensive layer of aeolian sand. This sand was eroded to a planar surface before developing a sand-pararendzina, which represents a second period of surface stability. The third deposit, a discontinuous dune sand, is presently also developing a sand-pararendzina. Difficulties of using ¹⁴C dates to erect absolute chronologies are discussed.     

Thermoluminescence dating of Dimlington Stadial deposits in eastern England

The loess component of a solifluction deposit of the Dimlington Stadial exposed at the inland site of Eppleworth in eastern England gave a thermoluminescence date of 17.5 ± 1.6 × 10³ years. The solifluction deposit is overlain by a slightly weathered till correlated with the Skipsea Till of coastal exposures. which lies between organic horizons with radiocarbon dates of 18,500–18,240 B.P. and 13,045 B.P. Although the till must have been deposited during the Dimlington Stadial (after 18,240 B.P. at Dimlington and after 17,500 B.P. at Epplcworth), it gave apparent TL dates of 42.1 ± 3.6 × 10³ years at Eppleworth and 102 ± 9 × 10³ years at Dimlington, indicating that the components of the till were not exposed to light immediately before deposition.     

Pleistocene glaciation of volcano Ajusco,central Mexico,and comparison with the standard Mexican glacial sequence

Three Pleistocene glaciations and two Holocene Neoglacial advances occurred on volcano Ajusco in central Mexico. Lateral moraines of the oldest glaciation, the Marqués, above 3250 m are made of light-gray indurated till and are extensively modified by erosion. Below 3200 m the till is dark red, decomposed, and buried beneath volcanic colluvium and tephra. Very strongly to strongly developed soil profiles (Inceptisols) have formed in the Marqués till and in overlying colluvia and tephra. Large sharp-crested moraines of the second glaciation, the Santo Tomás, above 3300 m are composed of pale-brown firm till and are somewhat eroded by gullies. Below 3250 m the till is light reddish brown, cemented, and weathered. Less-strongly developed soil profiles (Inceptisols) have formed in the Santo Tomás till and in overlying colluvia and tephra. Narrow-crested moraines of yellowish-brown loose till of the third glaciation, the Albergue, are uneroded. Weakly developed soil profiles (Inceptisols) in the Albergue till have black ash in the upper horizon. Two small Neoglacial moraines of yellowish-brown bouldery till on the cirque floor of the largest valley support weakly developed soil profiles with only A and Cox horizons and no ash in the upper soil horizons. Radiocarbon dating of organic matter of the B horizons developed in tills, volcanic ash, and colluvial volcanic sand includes ages for both the soil-organic residue and the humic-acid fraction, with differences from 140 to 660 yr. The dating provides minimum ages of about 27,000 yr for the Marqués glaciation and about 25,000 yr for the Santo Tomás glaciation. Dates for the overlying tephra indicate a complex volcanic history for at least another 15,000 yr. Comparison of the Ajusco glacial sequence with that on Iztaccíhuatl to the east suggests that the Marqués and Santo Tomás glaciations may be equivalent to the Diamantes glaciation First and Second advances, the Albergue to the Alcalican glaciations, and the Neoglacial to the Ayolotepito advances.     

Comparisons of 210Pb and pollen methods for determining rates of estuarine sediment accumulation

Comparisons of sedimentation rates obtained by ²¹⁰Pb and pollen analyses of 1-m cores collected throughout the Potomac Estuary show good agreement in the majority of cores that can be analyzed by both methods. Most of the discrepancy between the methods can be explained by the analytical precision of the ²¹⁰Pb method and by the exactness with which time horizons can be identified and dated for the pollen method. X-radiographs of the cores and the distinctness of the pollen horizons preclude significant displacement by reworking and/or mixing of sediments. Differences between the methods are greatest where uncertainties exist in assigning a rate by one or both methods (i.e., ²¹⁰Pb trends and/or “possible” horizon assignments). Both methods show the same relative rates, with greater sediment accumulation more common in the upper and middle estuary and less toward the mouth. The results indicate that geochronologic studies of estuarine sediments should be preceded by careful observation of sedimentary structures, preferably by X-radiography, to evaluate the extent of mixing of the sediments. Time horizons, whether paleontologic or isotopic, are generally blurred where mixing has occurred, precluding precise identification. Whenever possible, two methods should be used for dating sediments because a rate, albeit erroneous, can be obtained isotopically in sediments that are mixed; accurate sedimentation rates are also difficult to determine where the time boundary is a zone rather than a horizon, where the historical record does not provide a precise date for the pollen horizon, or where scouring has removed some of the sediment above a dated pollen horizon.     

中国西部天山高山带冷生土壤及相关土壤的地貌发生学

The soil landscape relationship was investigated in the Upper Urumqi River Basin of the Tienshan Mountain Range, Xinjiang, China. Cryosols occurred in glaciated valleys and north-facing toeslopes at elevations above 3 000 m. Most cryosols developed in moraine are Aquiturbels. The microrelief is dominated by earth hummocks, thus the surface organic layers are either discontinuous or broken due to frost action. The Bg horizons are either gleyed or mottled and frost-churned organic matter is common in the lower Bg horizons. Stratified horizons and buried organic or A horizons are also common on gentle sloping or undulating moraines indicating the effects of gelifluction. Reticular structures formed in the lower active layers due to ice lens formation and freeze-thaw cycles. The active layer thickness ranges from 140～200 cm. The organic cryosols (Hemistels) occur in depressions and north-facing toeslopes with an active layer thickness ranging from 90～110 cm. Soils formed on south-facing slopes have a mollic epipedon 20～25 cm thick and a strong brown cambic horizon and are classified as Haplocryolls. The distribution of cryosols is smaller as compared with the extent of permafrost due to the depth requirement of permafrost in cryosol classification. However, the existence of permafrost at greater depth cannot be ignored in land use interpretations.     

A radiocarbon-dated Ancylus transgression site in south-eastern Finland

A previously studied site at Hangassuo in the commune of Anjalankoski, formerly Sippola, in south-eastern Finland has been re-examined. The basal layers of the profile contain a clay-gyttja horzon deposited on peat, indicative of the Ancylus Lake transgression. A date of approx. 9500 B.P. was obtained for the lower peat layer, deposited after isolation of the basin during the Yoldia phase, and a date of 9280 ± 190 B.P. for the lower part of the transgression horizon. The upper part gave a date of 8870 ± 170 B.P. These dates suggest that the beginning of the Ancylus Lake phase and the Ancylus transgression occurred considerably earlier than has previously been suggested in the Late Quaternary chronology for Finland. The appearance of Alnus in the area is also dated. The pollen curve begins at 8360 ± 190 B.P. and the major increase of the species occurs at 7810 ± 180 B.P.
The events in the history of the Ancylus Lake and problems connected with these are discussed.     

The Firestone Sill ganister,Namurian, northern England—the A2 horizon of a podzol or podzolic palaeosol

The Firestone Sill is a sandstone of early Namurian age which outcrops in the northern Pennines. Occasionally the top of this sandstone contains a conspicuous white quartz arenite upto 1.5 m thick. This was formerly worked for refractory purposes and became known as the Firestone Sill ganister. The presence of roots, rootlets, soil horizons and pedogenically produced structures, e.g. cutans associated with the quartz arenite suggest that it represents the A₂ (eluvial) horizon of a podzol or podzolic palaeosol. The main processes operating during pedogenesis were the accumulation and incorporation of organic matter into the surface (A₁) horizon, destruction of sedimentary structures by bioturbation (principally rootlets), and the downward translocation of carbonaceous material, clays and other mineral breakdown products. The latter led to a relative quartz enrichment of a few percent in the A₂ (ganister) horizon and resulted in the development of a B-horizon of accumulation.The presence of occasional feldspars in the A₂-horizon and the rather small amount of quartz enrichment which took place in this zone suggest that pedogenesis was of fairly brief duration.     

The identification, lateral variation, and chronology of two buried paleocatenas at Woodhall Spa and West Runton, England

Two buried paleocatenas were studied to determine some features and techniques by which buried soils could be recognized, and to define their pedological characteristics, their lateral variation, and their contemporary environment. At Woodhall Spa, Lincolnshire, a ferric podzol to sandy gley sequence was developed in sands under marine clay and fen peat. The peat was radiocarbon dated at about 4100 yr BP. The buried soil was evident from its obvious catenary character and the soil characteristics and contemporary environment were determined using sand mineralogy, micromorphology, and pollen analysis. At West Runton, Norfolk, an apparently similar ferric podzol sequence occurred in Beestonian sands and gravels under a layer of Cromerian organic muds. However, only the uppermost profile contained definite evidence of soil formation. Other lower profiles contained pseudosoil features produced by sedimentation or diagenetic subsurface iron mobilization. It is suggested that the occurrence of a paleocatena is the most important criterion for the identification of a buried soil. Sedimentation and diagenesis cannot reproduce this lateral variation.     

The soils on the calcareous sand dunes southeast of South Australia

 The properties of soils on previously dated sand dunes from Robe to Naracoorte in South Australia were examined. In these areas younger sand dunes are composed of fresh sand, but older sand dunes are composed of calcarenited sand. The soils on the sand dunes developed successionally by the age of sand dunes. The soil properties of these sand dunes differ depending on the ages of the sand dunes. The properties of sand particles in soils are as follows: (1) On the sand dunes of 4300 years B.P., A/C profile developed (Rendzina). On the sand dunes older than 125 000 years B.P. and on the plateau of Tertiary limestone, soil profiles of A₁/AB/B/C on the sand dunes of 83 000 years B.P. and A₁/A₃/B₁/B₂/C (Terra rossa) are well developed. (2) Within the sand of A/C horizons of the sand dunes with the age of 4300 year B.P., the calcite grain content is about 64%, and the quartz content is about 35%. Within the B horizons of soils on the dunes from 83 000 years B.P. to 347 000 years B.P., the calcite grain content is only 1–2%; however, the quartz grain content is about 92%. In the B₂ horizons of soils on the dune of 690 000 years B.P. and on the Tertiary plateau, there are some calcite grains but the quartz grain content is about 96%. (3) The average size of quartz grains in the soils on the sand dunes from 4300 B.P. to 347 000 years B.P. is generally smaller, but the average size of quartz on the sand dunes of 690 000 year B.P. becomes larger and the grains are well rounded. On the Tertiary limestone plateau, the average quartz size becomes again smaller, and the grains are more rounded. (4) Fe_t in B₂ horizon of the soil profiles increases clearly corresponding to the age. Iron activity expressed by Fe_o/Fe_d also shows a close relation to the chronological sequence. The B horizon of the soil profiles shows a drastic decrease of Fe_o/Fe_d according to the age. Iron crystalinity, (Fe_d-Fe_o)/Fe_t, has a tendency for a positive relation with increasing age. Received: 1 June 1995 · Accepted: 4 December 1995     

陕西渭南北庄村晚更新世晚期古植被的再研究

通过渭南北庄村约31,000—18,000aB.P.沉积物中花粉百分含量、浓度和沉积率分析,对该时期古植被取得一些新认识,即当时云杉、冷杉等亚高山针叶树可能并未形成较大面积的森林,而是呈岛状分布于水体周围,并与区域性蒿草草原呈镶嵌状分布,植被并不稳定,亚高山针叶树曾两度出现又消失。从20,000aB.P.无乔木花粉出现,到18,000aB.P.难以找到任何花粉,本区变为无乔木生长的荒漠草原,气候曾经过数次冷偏湿与冷干的交替后,从18,000aB.P.起变得极度干燥和寒冷。     

Holocene alluvial stratigraphy in the upper Susquehanna River Basin, New York

Two alluvial terraces and the present flood plain were studied at two locations along the Susquehanna and Unadilla Rivers in south-central New York state. They have formed since deglaciation and incision of the stream channels into the valley train deposits. The higher terrace has noncumulative soil profiles with well-developed color B horizons predominantly of silt loam and very fine sandy loam. The terrace is weathered to a degree similar to nearby glacial outwash terraces that have caps of similarly textured sediments. Incision that produced the terrace occurred before 9705 ± 130 yr B.P. The lower terrace is characterized by relatively thick, vertical-accretion deposits of silt loam that contain sequences of thin, buried A, color B, and C horizons. They were formed between about 3240 ± 110 (¹⁴C data of soil humin) and 235 ± 80 yr B.P. Deposits above the 235 ± 80 yr B.P. stratum are unweathered. The soil stratigraphy and ¹⁴C dates of soil humin from buried A horizons are surprisingly well correlated between sites. Most sediments of the present flood plain have been deposited since 1120 ± 80 yr B.P. Incipient A horizons and oxidation of inherited organic matter in the subsoil are the only evidence of pedogenesis in the flood-plain deposits that are older than 275 ± 80 yr B.P. The most recent flood-plain fill deposited since then is unaltered. These youngest sediments of the flood plain along with the youngest veneer of vertical-accretion deposits on the lowest terrace are associated with an increased rate of deposition largely attributable to clearing of the forests by settlers, beginning in the late 1700s. Comparison of the alluvial stratigraphy with the radiocarbon-dated pollen stratigraphy of southwestern New York (Miller 1973) reveals some apparent time correlations between alluvial events and vegetation changes. This gives reason to speculate that climatic change or forest catastrophes such as disease or drought are causes of some of the alluvial events.     

Geochemistry of mineralization with exchangeable REY in the weathering crusts of granitic rocks in South China

Mineralization with exchangeable rare earth element (REE) and yttrium (MEX-REY) has been recognized in the weathering profiles in South China since the early 1970's. This type of REY mineralization occurs in weathering profiles of parent rocks ranging in composition from granite to acidic volcanic rocks and lamprophyre. The majority of the known resources occurring in the weathering profiles of granitic rocks. Total resources of this type of REY amount to millions tons of rare earth oxides, and therefore represent one of the most important types of rare earth resources in China, particularly for heavy rare earth elements (HREE) and yttrium.Accumulation of REY in the weathering profiles of granitic rocks is strongly controlled by the resistance to weathering of the principal REY-bearing accessory minerals in the parent rocks; only a limited proportion of total REY (< 30%) is incorporated in the rock-forming minerals. MEX-REY more commonly occur in weathering profiles developed on granitic rocks within which most of the REY are incorporated in accessory minerals weakly resistant to weathering (doverite, parisite, etc.). For the well-developed weathering profiles, three horizons can be distinguished from surface downwards: the lateritic horizon (A), the weathered horizon (B), and the weathering front (C). Continuous leaching, coupled with low rate of denudation, results in the accumulation of REY in the subsurface horizons (the B and C horizons), and thus results in REE differentiation within the well-developed, layered, and mature weathering profiles. Exchangeable REY, which can be replaced by cations like NH⁴⁺ and Na⁺ etc. in electrolyte solutions and can be removed by complexing agents such as EDTA, are commonly the major form of REE occurrence in the B horizon. Cerium is enriched in the top layer (A horizon) and depleted in the subsurface horizons of the weathering profiles, most likely due to the oxidation of Ce(III) to Ce(IV) followed by cerianite formation or absorption onto clays and/or Fe and Al oxyhydroxides.