loess mantle spatial variability and soil horizonation southern wisconsin usa abstract loess is an important quaternary sediment that records evidence of landscape instability in sediment source areas and landscape stability in accumulation areas in wisconsin usa loess mantles glaciogenic deposits dating to the last glaciation but the landscape distribution and effects of the loess mantle on soil formation have received very little attention this study investigates the influence of glacial landforms on the spatial pattern of loess thickness and how the presence or absence of a loess mantle overlying glaciogenic sediments has influenced soil profile morphology namely thickness and nature of horizonation loess thickness follows systematic trends along hillslopes with slope percentage explaining most loess thickness variation between summit and backslope positions in the presence of a loess mantle solum and bt horizon thickness is proportional to the thickness of the loess mantle in well drained profiles in the absence of a loess mantle landscape and sediment characteristics that control permeability and water throughflow appear to be the most important determinants of profile characteristics the loess mantle modulates soil formation above the lithologic discontinuity with sandy calcareous glacial sediments by controlling soil water behavior and having physical and chemical characteristics conducive to transformation to soil genetic horizons

soil development on a beach ridge chronosequence in the gulf of mexico coastal plain and its relation to the ancient land use abstract a soil chronosequence study is presented in a beach ridge system at the mouth of the usumacinta and grijalva rivers mexico formed since a strong decrease in the rate of sea level rise some 6000 years ago four sites were selected for the chronosequence study simon sarlat ss rancho magdaleno 1 and 2 rm1 rm2 cocoteros cc and playa cocoteros pc located on beach ridges that range in age between 5000 years old to recently formed the soils show poor to moderate degree of development and the change in the pedogenic properties has been clearly evaluated the most pronounced changes are the following from the older ss rm2 to the younger soils pc cc color becoming yellowish brown in the better developed soils an increase in the amount of organic matter clay and fed iron extracted with dithionite solution a better structure with more stable aggregates a decrease in the feo proportion fe extracted with oxalate solutions and an increase in the content of fine magnetic particles formed by pedogenesis this area was densely populated and thus affected by human activities since the pre classic period 800 300 bc as many archaeological sites have been registered we evaluated soil agronomic quality in order to understand the ancient land use the results show that the soils in this area no matter their age have low agronomic quality which must have limited their use by ancient population however the strategic position near main trade routes near rich aquatic resources and a low susceptibility to flooding were favorable for human settlement on the beach ridges

soil chronosequence of brasstown creek blue ridge mountains usa abstract a chronosequence of soils on alluvial terraces in the appalachian highlands of the southeastern united states is identified by simple methods of quantitative soil morphology and chemical analysis the chronosequence is from brasstown creek a 5th order stream draining 65 km 2 of the blue ridge mountains of north georgia the portion of the valley studied is about 1 km wide and contains five quaternary terrace remnants radiocarbon dates show that the floodplain t0 is late holocene and includes historical post ca 1830 a d sediment and the four older terraces t1 t5 are pre holocene the floodplain soils are either entisols in historical sediment or buried inceptisols with weak bw horizons in late holocene to protohistoric sediment the lowest terrace t1 is terminal pleistocene in age and its soils have bt horizons that are about 0 9 m thick 10yr 4 5 to 10yr 5 4 in colour and contain 25 to 35 clay soils on terraces older than t1 become progressively redder and contain more clay with increasing age culminating with 2 5yr hues and 40 to 52 clay in the bt horizon of t5 percent clay in bt horizons rubification indices iron oxide contents and element ratios progressively change with age of the terraces but other morphological properties ph and individual element concentrations are of less use as chronosequence variables

soil development on marine terraces near metaponto gulf of taranto southern italy abstract for decades the marine terraces in the metaponto area have been the subject of discussions concerning their number sedimentology genesis and age this paper contributes to landscape history reconstruction from a pedogenetic view the marine terraces are generally covered by loamy sediments which have been interpreted in previous works as lagoonal and or alluvial sediments deposited shortly after the emergence of the land surface above sea level pedogenetic investigation including field observations e g soil colour intensity of weathering precipitation of secondary carbonates and fed fet ratio silt clay ratio and carbonate content reveals that the usual sedimentation history on the terraces includes a period of soil formation between the deposition of the marine and that of the alluvial sediments most likely soil formation began after the relative sea level maximum within the same interglacial during which the marine terrace formed later alluvial sediments accumulated during a time of periodic flooding while soil development in the underlying marine sediments probably continued at reduced rates one central question of this study is whether soil formation indicates progressive ages of the terraces the complex landscape history involving several sedimentation and erosion phases makes the correlation of soil development stages with terrace ages difficult nevertheless maximum fed fet ratios and ca mg k na al ratios of the soils developed in the different sediments plotted vs assumed terrace age indicate increasing soil development the relationship between fed fet ratios and terrace age can be best described by power r2 0 89 or logarithmic functions r2 0 72 both describing a strong increase in pedogenic iron in the first 100 ka which slows down afterwards ca mg k na al ratios follow a logarithmic decrease with time r2 0 99 indicating progressive silicate weathering associated with element release and leaching

a comparison of quaternary soil chronosequences from the ionian and tyrrhenian coasts of calabria southern italy rates of soil development and geomorphic dynamics abstract soil development during the quaternary was investigated by comparing and integrating analytical datasets of three soil chronosequences developed on different terrace staircases along the tyrrhenian western and ionian eastern coasts of northern calabria southern italy two of these soil chronosequences developed on early to late pleistocene marine terraces in two sectors of the praia area western coast whereas the third one developed on fluvial terraces in the rossano area eastern coast spanning from middle to late pleistocene ages respectively we present and discuss both novel results and already published data related to selected morphological physical chemical mineralogical and sem analyses from the two coastal sectors we explored the effects of time on soil development trying to unravel the role of soil forming processes parent material and geomorphic dynamics on direction and rates of pedogenesis a complex nature of parent materials was indicated by the geochemical signature coupling certain similarities with some heterogeneity between the two study sectors but also across single soil profiles as a response to morphodynamic processes soil reworking aggradation burial and or erosion in turn promoting soil ageing and or rejuvenation these processes and lithological discontinuities were also responsible for some data scattering from calculated soil chronofunctions for peculiar soil properties and pedogenic indices plotted against estimated soil ages among the main outcomes good positive correlations were obtained for the fed feo fet and fed fet indices weighted on the basis of total soil profile and single horizon thicknesses to minimize the effects of soil truncation by erosion processes our results confirm the reliability of these indices as soil development indicators moreover they suggest that i rates of soil development did not change significantly over ca 100 800 ka despite the cyclical alternation of pleistocene climate changes ii dominant soil forming processes tend to minimize original differences of pedogenic substrata and local pedo climatic conditions through time in addition soil chronofunctions permitted to estimate the unknown age the time range of soil development before burial about 200 ky of a buried soil profile in the rossano area not correlated to any terrace surface of known age the occurrence of etched quartz grains in soils of different ages for the two study sectors clearly indicates different rates of silica dissolution in the tyrrhenian and ionian coasts of calabria promoted by different climatic and pedoenvironmental conditions

composition properties and formation of pseudogley on loess along a precipitation gradient in the pannonian region of croatia abstract three pseudogley profiles stagnic cutanic albeluvisol dystric siltic stagnic cutanic albeluvisol eutric siltic and luvic stagnosol hypereutric siltic were studied along the 700 1000 mm mean annual precipitation map gradient in the pannonian region of croatia the aim was to compare their composition and properties and to determine the major processes of their formation as well as to show whether investigations of pseudogley climosequences in this part of pannonian basin are feasible all three soil profiles were formed in situ from initially vertically homogeneous previously cycled and post depositionally modified loess deposits of same provenance given their morphology texture geochemical ratios and mineralogy substantial morphological and physical a horizons colors eg horizons thicknesses colors bulk densities and porosities btg horizons redoximorphic features as well as chemical soil properties ph base saturation topsoil organic c content corresponded to the precipitation gradient on the other hand due to slight differences between their parent materials clay content and cec values of the investigated profiles did not increase with the increase of map nevertheless processes of acidification and pseudogleying were found to be least pronounced at the location with the lowest map and most pronounced at the location with the highest map intensity of lessivage as one of major pedogenetic processes in all three investigated pseudogleys did not correspond to the precipitation gradient since it was more a function of soil ph and clay mineralogy than map the three pedogenetic processes were recognized on the basis of obtained ph base saturation cia chemical index of alteration and ti al values as well as soil texture morphology presence and characteristics of clay coatings and redoximorphic features and phyllosilicate dynamics comminution of chlorite into the clay fraction vermiculitization smectite translocation observed along the investigated profiles given the uneven environmental conditions of loess depositions across the pannonian region of croatia and the resulting incomplete uniformity of loess parent materials investigations of pseudogley climosequences in this part of the pannonian basin should be approached with caution

pseudogleyed loess derivates the most common soil parent materials in the pannonian region of croatia abstract loess derived sediments represent the most widespread soil parent materials in the pannonian region of croatia pseudogley as the most common soil type in this region developed mainly on such parent materials pseudogleys largely correlate with the wrb reference soil group of stagnosols on the general soil map of croatia at scale 1 50 000 gsm of croatia the distinction is made between pleistocene loams pl and loess as pseudogley parent materials the initial purpose of this research was to investigate if the criteria for this distinction were clear and consistent and if the terms used for labeling these parent materials were adequate hence we investigated parent materials of 18 pseudogleys across 6 different locations three on loess and three on pl in the pannonian region of croatia we analyzed their morphology including micromorphology of three representative parent materials particle size distribution total porosity ph and mineral assemblages by modal analysis of three representative parent materials following these analyses no systematic differences between the loess parent materials and the pl parent materials were found additionally it was concluded that due to significant geogenetic and or pedogenetic alterations of all studied parent materials none of them should be labeled simply as loess hence parent material at one location was labeled as leached loess derivate and parent materials at all other locations were labeled as pseudogleyed loess derivates both types of parent materials were described in detail and defined in addition the terminology and the classification of loess derived parent materials in general was proposed the analyzed pseudogleyed loess derivates were not completely uniform across the investigated locations primarily this was due to the polygenesis of loess reflected by differences in particle size distributions and compositions of light and heavy mineral fractions secondarily it was due to the 600 1100 mm map gradient along the study region reflected by differences in ph values and properties of redoximorphic features although pedogenesis of the investigated parent materials might have started already during the late glacial and have continued throughout the holocene at varying and overall decreasing rates their morphology indicates that pseudogleization and lessivage are still active processes which occur simultaneously in the analyzed parent materials and agree with the present climate

triassic vertebrates of gondwanan aspect from the richmond basin of virginia a new locality of early late triassic age in the richmond basin of east central virginia has yielded abundant remains of a diversified assemblage of small to medium sized tetrapods that closely resembles southern hemisphere gondwanan assemblages in the predominance of certain synapsids associated palynomorphs indicate an early middle carnian age for the fossiliferous strata the discovery suggests that previously recognized differences between tetrapod assemblages of early late triassic age from gondwana and laurasia at least in part reflect differences in stratigraphic age rather than geographic separation

antler elastics in the canadian cordillera during late devonian through mid mississippian time thick sequences of elastics flooded the canadian cordilleran miogeocline chert conglomerate chert quartz sandstone and pebbly mudstone of the westerly derived earn sequence formed local massive channel deposits up to 200 m thick on submarine fans and in narrow grabens within a broad region of shale deposition extension and local contraction of the miogeocline during rifting or strike slip outboard of present preserved limits can explain 1 the derivation of earn elastics from older miogeoclinal units 2 local alkaline volcanism 3 exhalite mineralization and 4 tremendous thickness variations related to steep syndepositional faults

paleoenvironmental reconstruction based on soils buried under scythian fortification in the southern forest steppe area of the east european plain abstract landscape response to late holocene climatic cycles is based on detailed hierarchical morphological analytical and micro biomorphic research of a soil chronosequence which included a soil buried under a fortification earth wall of the early iron age luvic chernozem and a surface soil chernic greyzemic luvic phaeozem in the southern forest steppe area of the east european plain both soils formed on similar surfaces with the same lithology non carbonate loess underlain by carbonate loess at the same elevation and in close proximity to each other the buried soil was truncated by at 40 cm and transformed by diagenesis taking this into account it was possible to reconstruct the soil formed by the time of burial under the earth wall and to classify it as chernic luvic phaeozem both surface and buried soils are polygenetic combining the features of humid forest and steppe pedogenesis the radiocarbon data obtained from the humic horizon of the buried soil 6750 120 years calbp allows bracketing the steppe environment to the mid holocene atlantic period pedogenetic evolution since the early iron age included the next stage of clay illuviation formation of thin hypo coatings and the development of greyzemic features the studied phaeozems indicate relative landscape stability at the southern boundary of the forest steppe zone

albeluvisol development with time in loamy marine sediments of southern norway abstract this paper reports a study on soil development in loamy marine sediments on both sides of the oslofjord vestfold ostfold this region has been subject to steady glacio isostatic uplift during the whole holocene hence land surface age continuously increases from the coast inland several sea level curves based on radiocarbon datings enable estimation of land surface age for all locations clay illuviation starts in less than 1650 years e horizons become lighter with age but their lower boundary stays around 40 cm for more than 10 000 years albeluvic tongues develop between 4600 and 6200 years initially they form along intersections of cracks as preferential flow and leaching along the cracks continues the tongues increase in length and width progressively consuming the prisms between the cracks in the upper bt horizon the fe d fe t ratios weighted means of the upper meter show a clear linear increase with soil age and may be used for pedo dating i e for estimating the ages of non dated land surfaces covered with similar sediments in contrast the logarithmic decrease of base saturation and ph with rapid changes in the first time but only very slight changes between 2000 and 10 000 years makes these parameters unsuitable for pedo dating

climate vs parent material which is the key of stagnosol diversity in croatia abstract stagnosols are the most widespread soils in the pannonian region of croatia in croatia they are referred to as pseudogleys and considered to form primarily by normal top down pedogenesis however the formation of their non calcareous loess parent materials probably involved different sources transports and depositional environments we aimed to determine the courses of soil formation and the characteristics of three stagnosol profiles studied along the mean annual precipitation map gradient 700 1100 mm in the pannonian region of croatia we found that soil redoximorphic features formed in situ by ongoing pseudogleization vertical trends for the clay silt and coarse fine silt ratios pointed to top down pedogenesis however high organic c content at the bottom of one soil profile is the result of erosion sedimentation processes whereas high clay content in the subsoil of another profile was largely the result of sedimentation in a shallow paleo lake therefore some croatian stagnosols should be considered polygenetic each soil profile was classified using the wrb system and the new wrb 2014 version proved more suitable than the previous one wrb 2006 however suggestions for improvements are given in line with the map gradient were several morphological and only two chemical ph and base saturation soil characteristics organic c content did not correspond to map due to variability of forest topsoils clay content and cec did not agree with map due to variability of loess parent materials across the pannonian region of croatia the existence of more than one source of loess material confirmed by the modal analysis and the differences in depositional paleo environments resulted in slightly different mechanical compositions of the investigated parent materials we concluded that both climate and parent material must be regarded as key factors for the formation and characteristics of stagnosols in the pannonian region of croatia and the wider southwestern pannonian basin

classification and distribution of soils with albic horizons in the usa a preliminary analysis abstract the albic horizon a diagnostic subsurface horizon that is comprised of primary sand and silt particles that are light colored because they lack clay or iron oxide coatings is unique in that it is an eluvial horizon that is defined on the basis of a loss rather than a gain of weathering products over 3000 official soil descriptions were examined in the us natural resources conservation service databases to identify which taxa contain albic horizons albic horizons are present i e more than 8 soil series in seven orders 28 suborders 73 great groups and about 1600 soil series in soil taxonomy orders with albic horizons can be ranked on an area basis alfisols spodosols ultisols mollisols inceptisols entisols aridisols the mean thickness of the albic horizon is 19 cm with the greatest thickness in alorthods 90 cm and the least in xerolls 3 1 humods 4 0 and ustolls 5 6 cm albic horizons may occupy one or two of several positions in the soil profile including i the mineral soil surface ii below an a horizon iii as a buried horizon iv between a variety of diagnostic subsurface horizons in bisequal soils and v in some soils with alternating e and bt lamellae albic horizons separate or are underlain mainly by an argillic or a spodic horizon half 50 of the soils with albic horizons are excessively to well drained many albic horizons have been lost due to cultivation especially in aqualfs udalfs and udults

deposition and pedogenesis of periglacial sediments and buried soils at the serpentine hot springs archaeological site seward peninsula ak abstract soil micromorphology is an excellent tool for relating quantitative laboratory data to soil development in complex pedogenic settings this study utilizes micromorphology scanning electron microscopy bulk soil geochemistry clay mineralogy and particle size analysis to reconstruct the depositional and pedogenic history of the serpentine hot springs fluted point site on the seward peninsula alaska sediment deposition occurred via colluviation which dominated during the late glacial period and early to middle holocene and aeolian processes which dominated during the younger dryas yd and late holocene two buried soils are present one dating to the holocene thermal maximum htm and the other dating just before the neoglacial period pedofeatures fall into four categories 1 cryogenic features 2 clay illuviation features 3 podzolization redox features and 4 anthropogenic features the spatial relationships among these features provides insight into the pedogenic history of the soil the htm soil is characterized by clay illuviation suggesting warm mildly acidic well drained soil conditions the pre neoglacial soil is characterized by incipient placic horizon development and podzolization indicative of moist acidic variably drained conditions cryogenic features associated with late holocene neoglaciation dominate the modern soil despite cryogenic activity and the presence of permafrost the cultural stratigraphy of the site remains intact

testing a soil development model against southern norway soil chronosequences abstract the first results of modeling soil development in marine sediments in s norway using the model soilgen are compared to measured properties of two soil chronosequences on the western and eastern side of oslofjord respectively the aim of this work is to test how well soil development under well defined environmental conditions can be modeled such testing reveals to what degree soil forming processes are understood allowing formulation of adequate calculations reflecting these processes the model predicts particle size distribution reasonably well although clay depletion in the upper parts of the soils as a result of clay migration is overestimated the model tends to underestimate contents of organic carbon and cec in the a horizons below modeled cec matches well with measured cec base saturation is overestimated in the upper 40 cm and underestimated below apparently leaching of bases proceeds less rapidly in reality than is predicted by the model due to strong soil structure of the b horizons causing preferential flow and base leaching around the aggregates whereas bases inside the aggregates are only slightly affected by leaching difficulties and possibilities for improvements are identified some related to model input data and some to the model itself input data could be improved by determining the amounts of organic carbon in organic surface horizons and by quantifying effects of bioturbation a big challenge is the implementation of soil structure formation in the model quantitative data on the development of soil structure with time that can be included in a model are required amounts distribution and connectivity of macro pores need to be defined for each stage of soil development and zones of low and high base leaching need to be distinguished in the model for each time step the long term aim of this work is to model soil development with different sets of soil forming factors e g different climatic conditions in order to reliably predict soil development under different climate scenarios and related sets of soil forming factors the results of the first model runs and the identified possible improvements suggest that this aim is generally achievable

quantitative aspects of carbonate leaching of soils with differing ages and climates abstract carbonate leaching rates in several soils in switzerland and in the lake constance region were calculated and related to landscape development the leached depth of the soil the carbonate content and the soil density profile are sensitive to soil age a first database of carbonate leaching and its relationship to soil age is presented a simple relationship between the amount of precipitation and carbonate losses was found water draining from calcareous soils from subarctic to temperate areas was usually close to equilibrium with calcite and dolomite thus the annual amount of rainfall and consequently the percolation are the most important factors in carbonate leaching the influence of temperature is comparatively low carbonate dissolution rates amounted to approximately 1 7 3 0 mol m 2 year 1 if they are referred normalised to 1000 mm soil water fluxes soils on coarse parent material may have slightly lower carbonate dissolution rates in the order of approximately 1 7 2 2 mol m 2 year 1 normalised to a 1000 mm output while other sites with smaller grain sizes had slightly higher dissolution rates 2 2 3 0 mol m 2 year 1

soils as a tool for estimating ages of quaternary fault scarps in a hyperarid environment the southern arava valley the dead sea rift israel abstract on the alluvial fan of nahal shehoret in the extremely arid region of the negev desert israel reg soils developed on stable alluvial surfaces in colluvium along terrace risers and in colluvial units on a complex fault scarp were compared the degree of soil profile development provided an age estimate of the surface that was faulted a maximum age estimate of the scarp or terrace riser and an estimate of the maximum recurrence intervals of faulting events irsl dates of the tectonically displaced alluvial surfaces and colluvial units at the same site enabled us to re evaluate the use of reg soils for relative dating the major faulting event started at 34 8 4 3 ka it displaced a late pleistocene surface of the nahal shehoret alluvial fan dated at 56 10 8 ka renewed fluvial activity and deposition of alluvium on the downfaulted block had almost terminated by 13 6 2 3 ka the scarp was formed during the latest pleistocene and was followed by smaller faulting events which had only minor effects on the fault scarp morphology the similarity of age estimates from irsl dating and the degree of soil development in this environment indicates that soils can be used to date surfaces and colluvial units

an unusual new archosauromorph reptile from the upper triassic wolfville formation of nova scotia an unusual new reptile teraterpeton hrynewichorum is described based on a partial skeleton the holotype comes from the upper triassic wolfville formation newark supergroup of nova scotia the temporal region of the skull is of the euryapsid type the premaxillary rostrum and dentary symphysis are elongate and edentulous the dentition comprises distinctive occluding upper and lower teeth a phylogenetic analysis shows that teraterpeton hrynewichorum is an archosauromorph reptile trilophosaurus buettneri from the upper triassic dockum group of texas may represent a closely related species

periglacial slope deposits and their pedogenic implications in germany abstract 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

alluvial soil chronosequence in the inner coastal plain central virginia abstract a chronological sequence of soils formed on a series of alluvial depositional surfaces ranging in age from late middle miocene to late pleistocene was characterized to clarify soil geomorphic relations and provide a basis for allostratigraphic subdivision of the inner coastal plain on quaternary river terraces ultic hapludalfs containing abundant weatherable mineral species and clast types are estimated to have formed in 60 000 120 000 yr whereas typic hapludults greatly depleted in weatherable minerals and showing strong weathering of clast types are estimated to be 700 000 1 600 000 yr old typic paleudults with incipient plinthite duripan and ferricrete development characterize interfluves that have been little eroded since early pliocene time 3 4 5 3 myr ago typic plinthic paleudults with intense weathering of siliceous clasts and moderate to strong duripan and ferricrete development are found on surfaces that formed near the beginning of late miocene time 10 8 13 0 myr ago chemical weathering in the chronosequence may be classified into three progressive stages 1 decomposition of unstable sand and silt sized minerals into a mixed stable unstable clay mineral suite stable fe al si bulk chemical composition 107 yr not all soil properties show unidirectional development nor is a steady state of pedon development observed even after approximately 107 yr of chemical weathering soil development in the chronosequence is episodic the transition from one phase to the next is marked by a change in rate and sometimes a reversal in the direction of development of one or more soil properties

weathering trends in terrace deposits up to 350 000 years old in northeast southland new zealand abstract gravelly floodplain deposits and six terrace treads in the waimea plains northeast southland new zealand range in age from ca 1000 years old to 350 000 yr old deposits are progressively more weathered with increasing parent material age soils developed in them are classified as recent soils brown soils and ultic soils in the new zealand soil classification and udifluvents dystrochrepts haplohumults hapludults and paleudults in the usda soil classification soil taxonomy the youngest soils are slightly acid those developed in deposits 35 000 70 000 yr old are strongly acid in soils in deposits 160 000 yr old and older that have weathered in two or three interglacial periods including the present one ph and total exchangeable bases values are higher than in soils in younger deposits the higher ph of the soils in older deposits is attributed to release of cations by stone weathering soils developed in deposits up to 70 000 yr old have clays dominated by mica and chlorite stones in these soils are at most weakly weathered and the two phases of weathering are distinguished a phase of approximate duration 100 000 yr in which most weathering and leaching occurs in the matrix which becomes increasingly acidified and a phase from 100 000 to 350 000 yr which is dominated by cation release from stones reversal of the acidification trend and breakdown of stone fabric

initial stages of weathering and soil formation in the morteratsch proglacial area upper engadine switzerland investigations in alpine soils indicate that mineral weathering is much faster in young soils 1000 yr than in old soils 10 000 yr however little is known about the initial stages of weathering and soil formation i e during the first decades of soil genesis in this study we investigated rock forming minerals weathering at very early stages of soil formation due to the continuous retreat of the morteratsch glacier upper engadine swiss alps the proglacial area offers a full time sequence from 0 to 150 yr old surfaces a low slope and the absence of glacier which might have interrupted soil formation processes contributed to the choice of the morteratsch proglacial valley for this case study the area is well documented regarding vegetation and soils the tectonic unit is the bernina crystalline which is mainly constituted of granitoid rocks consequently the glacial till has an acidic character mineralogical measurements were carried out on the soil fraction 2 mm using xrd and drift for qualitative and quantitative phase analysis in addition chemical analyses of the stream water from the main channel tributaries and of rainwater were performed with a special focus on ca sr and sr isotope ratios 87sr 86sr furthermore the accumulation of organic matter within the time sequence and physical soil properties were measured decreasing grain size with time shows active physical weathering processes soil organic matter has been accumulated during 150 yr at very high rates special emphasis has been given to chemical weathering and to the formation and transformation mechanisms of minerals of special interest were biotite chlorite epidote plagioclase and calcite biotite has been continuously transformed into illite like components within 150 yr the concentration of epidote significantly decreased the high ca sr as well as 87sr 86sr ratios in the stream and spring waters confirmed that ca bearing minerals are weathering and transforming at very high rates in the proglacial area also in cryic ice free environments chemical weathering rates are high leading to the formation and transformation of minerals disseminated calcite in granitoid rocks not confined to sedimentary carbonate rocks also plays a role in subglacial environments it is however not known for how long such an influence is significant and measurable the high ca na and ca sr ratio in the stream and tributary waters showed that calcite contributes to the supply of soluble ca although the ion activity product calculations clearly demonstrated that the waters were undersaturated with respect to this mineral

neodymium isotope geochemistry of felsic volcanic and intrusive rocks from the yukon tanana terrane in the finlayson lake region yukon canada devonian mississippian felsic rocks from the finlayson lake region have variable geochemical and nd isotopic characteristics that provide insights into the tectonic and metallogenic evolution of the yukon tanana terrane ytt and the northern cordillera late devonian 365 360 ma calc alkaline and tholeiitic arc felsic rocks in the mafic dominated fire lake unit yield end350 4 8 and 0 1 respectively and have 1 49 1 94 ga depleted mantle model ages tdm devonian mississippian 360 356 ma felsic volcanic kudz ze kayah unit wolverine succession and intrusive rocks grass lakes suite associated with volcanogenic massive sulphide vms deposits have end350 7 8 to 9 5 with tdm 1 59 2 25 ga a granitoid sample from the early mississippian 350 345 ma simpson range plutonic suite has end350 12 9 and tdm 2 01 ga similar to previously reported values for this suite the vms associated grass lakes suite of granitoids has higher high field strength element hfse and rare earth element ree contents and higher zr sc zr tio2 nb la and zr la values relative to the simpson range plutonic suite these geochemical features are similar to coeval vms associated felsic volcanic rocks in the kudz ze kayah unit the identification of similar hfse ree enriched felsic volcanic and subvolcanic intrusive rocks may aid in delineating prospective regions for vms mineralization in the ytt and other continental margin arc to back arc environments the geochemical and nd isotopic data for these ytt felsic rocks suggest that they reflect episodic mid paleozoic arc fire lake unit simpson range plutonic suite and back arc magmatism kudz ze kudz unit wolverine succession built upon a transitional basement with variable but significant influence from evolved proterozoic crustal materials

global triassic tetrapod biostratigraphy and biochronology abstract eight temporally successive assemblage zones of tetrapod fossils provide the basis for dividing triassic time into eight land vertebrate faunachrons these land vertebrate faunachrons their type assemblage zones and their approximate correlation to the standard global chronostratigraphic scale are ascending order 1 lootsbergian lystrosaurus assemblage zone balfour katberg and burgersdorp formations karoo basin south africa late dorashamian induan 2 nonesian cynognathus assemblage zone burgersdorp formation karoo basin south africa olenikian 3 perovkan shansiodon assemblage zone donguz formation russian urals anisian 4 berdyankian mastodonsaurus assemblage zone bukobay formation russian urals ladinian early carnian 5 otischalkian paleorhinus assemblage zone chinle group chinle basin usa late early to early late carnian 6 adamanian rutiodon assemblage zone chinle group chinle basin usa latest carnian 7 revueltian pseudopalatus assemblage zone chinle group chinle basin usa norian 8 apachean redondasaurus assemblage zone chinle group chinle basin usa rhaetian the triassic land vertebrate faunachrons provide a framework for the correlation of triassic nonmarine deposits with a temporal resolution comparable to the seven triassic stage ages of the standard global chronostratigraphic scale

unusual tetrapod teeth from the upper triassic chinle formation arizona usa two teeth collected from the upper triasssic chinle formation of northeastern arizona are described here and named kraterokheirodon colberti gen et sp nov these teeth are novel in having an occlusal ridge with six cusps and a posterior shelf lacking dentine evidence for thecodont implantation of the root suggests amniote affinities for these teeth they do not match any teeth known for basal vertebrates or basal tetrapods although the teeth display some affinities with traversodont cynodonts there are significant differences that preclude a referral to this group these teeth most probably represent an unknown tetrapod clade and document the presence of a large amniote previ ously unknown from late triassic terrestrial faunas

isotopic age of the black forest bed petrified forest member chinle formation arizona an example of dating a continental sandstone zircons from the black forest bed petrified forest member chinle formation in petrified forest national park yield ages that range from late triassic to late archean grains were analyzed by multigrain tims thermal ionization mass spectrometry single crystal tims and shrimp sensitive high resolution ion microprobe multiple grain analysis yielded a discordia trajectory with a lower intercept of 207 6 2 ma which because of the nature of multiple grain sampling of a detrital bed is not considered conclusive analysis of 29 detrital zircon grains by tims yielded upb ages of 2706 6 6m a to 2066 6 ma eleven of these ages lie between 211 and 216 6 6 8 ma our statistical analysis of these grains indicates that the mean of the ages 213 6 1 7 ma reflects more analytical error than geologic variability in sources of the grains grains with ages of ca 1400 ma were derived from the widespread plutons of that age exposed throughout the southwestern cordillera and central united states twelve grains analyzed by shrimp provide 206 pb 238 u ages from 214 6 2m a to 200 6 4 ma we use these data to infer that cores of inherited material were present in many zircons and that single crystal analysis provides an accurate estimation of the age of the bed we further propose that even if some degree of reworking has occurred the very strong concentration of ages at ca 213 ma provides a maximum age for the black forest bed of 213 6 1 7 ma the actual age of the bed may be closer to 209 ma dating continental successions is very difficult when distinct ash beds are not clearly identified as is the case in the chinle formation detrital zircons in the black forest bed however are dominated by an acicular morphology with preserved delicate terminations the shape of these crystals and their inferred environment of deposition in slow water settings suggest that the crystals were not far removed from their site of deposition in space and likely not far in time plinian ash clouds derived from explosive eruptions along the early mesozoic cordilleran margin provided the crystals to the chinle basin where local conditions insured their preservation in the case of the black forest bed the products of one major eruption may dominate the volcanic contribution to the unit volcanic detritus in the chinle formation was derived from multiple distinct sources coarse pebble to cobble size material may have originated in eastern california and or western arizona where triassic plutons are exposed fine grained detritus in contrast was carried in ash clouds that derived from caldera eruptions in east central california or western nevada

quaternary soil chronosequences on terraces of the susquehanna river pennsylvania abstract susquehanna river terraces are used to establish time lines along a 150 km reach of the river from the lower piedmont to the edge of the appalachian plateau this is achieved by generating soil chronosequences at two locations marietta pa in the lower piedmont and muncy pa near the glacial border on the boundary between the valley and ridge province and the appalachian plateau these sites preserve the most complete record of fluvial incision on the susquehanna river with flights of seven quaternary terraces ranging in elevation from 3 m to 51 m above the modern river soil characteristics used to develop the soil chronosequences include complexity of horizonization thickness of b horizon clay content of b horizon soil color cbd extractable fe al and mn total extractable fe and clay mineralogy terrace age constraints are based on soil development correlation to regional glacial stratigraphy correlation to dated fluvial and glaciofluvial deposits and by paleomagnetic analysis of sediments terrace ages at the muncy site range from modern

saprolite soils and sediments in the rhenish massif as records of climate and landscape history abstract the rhenish massif at the western boundary of germany consists predominantly of devonian slates and siltstones which over large areas have been altered to saprolite the distribution and characteristics of saprolites pleistocene periglacial slope deposits ppsd holocene colluvium and soils were investigated along a 2 5 m deep gas pipeline ditch in 20 sections with an overall length of 19 km the results are used for landscape history reconstruction under warm humid conditions of the upper mesozoic and lower tertiary intensive weathering led to formation of a planation surface covered by thick saprolites and kaolinitic soils during pleistocene glaciations the area experienced periglacial conditions that resulted in erosion of the soils and parts of the saprolites several layers of ppsd developed during the holocene no significant slope processes occurred until human deforestation led to accelerated hillslope erosion as a result today the ppsd are partly eroded or covered by holocene colluvium in many places the sediment distribution follows distinct rules generally the sediment thickness increases downslope concave slope sections show a substantial increase in thickness and number of preserved sediment layers the soils developed in ppsd on saprolite are primarily planosols while cambisols and luvisols predominate in ppsd on fresh rock

soil formation in a quaternary terrace sequence of the allier limagne france macro and micromorphology particle size distribution chemistry abstract soil formation in a terrace chronosequence of nine gravelly quaternary terraces was studied based on macro and micromorphological mineralogical chemical and physical characteristics based on textural characteristics the c horizon of the youngest soil appears to be representative for the parent material of lower b and c horizons in the youngest soils and of all horizons in older soils the parent materials contain a volcanic and a granitic component with increasing age of soils the following stages of soil formation were observed holocene soils on lowest terraces show evidence for mixing of sedimentary layers by biological activity resulting in texturally homogeneous a and b horizons in the absence of periglacial processes soil formation in holocene and in late pleistocene terraces took place under continuously well drained conditions late pleistocene soils on higher terraces show effects of clay illuviation with prominent weathering features in a horizons middle and early pleistocene soils on the highest terraces were influenced by periglacial conditions and display effects of various cycles of soil forming processes alternated with periglacial processes increasing in complexity with age weathering of all minerals except quartz neoformation of clay and clay illuviation has resulted in distinct differentiation between sandy a and e horizons and a clayey b horizon periglacial processes during the quaternary weathering clay formation and clay illuviation have caused a considerable compaction and decreased water permeability this has resulted in imperfect drainage now reflected by abundant locally cemented iron and manganese oxide segregations in the surface horizon typical for surface water gley with evidence of ferrolysis ferrolysis the increased weathering of clay under influence of alternating oxidation reduction in the seasonally waterlogged surface soil may have further contributed to the marked textural change between a and e versus b horizons easily weatherable minerals observed in strongly leached surface layers of older end members of the terrace sequence might be attributed to aeolian volcanic inputs the holocene and late pleistocene soils are intensively used as arable land as a result of the continuously well drained conditions on account of the poor drainage the middle and early pleistocene soils are used mainly for grassland and forest

contrasting environmental memories in relict soils on different parent rocks in the south western italian alps abstract soils on the alps are usually weakly developed both because of the extensive pleistocene glaciations and because of slope steepness and climate enhancing erosion however on some stable relict surfaces particularly in the outermost sections of the alpine range some highly developed soils are apparently in contrast with holocene soil forming conditions in this work we assess the extent of pedogenesis in some of these soils located under montane level vegetation in the ligurian alps sw piemonte italy and relate it to the effects of climate and parent material the considered well developed profiles showed signs of extremely different pedogenetic processes on the different lithotypes in particular podzols with extremely thick e horizons up to more than 2 m thick and very hard thick ortstein or placic horizons were formed on quartzite reddish terra rossa luvisols were formed on limestone red extremely acidic alisols were formed on shales the chemical properties the micromorphology and the clay mineralogy demonstrated high intensity pedogenic trends and were characteristic of processes usually occurring under different climates they may therefore represent excellent pedo signatures of different specific past climatic environmental conditions as a response of different lithologies to specific soil forming environments which range from warm and humid climates typical of red alisols and luvisols to cool and humid wet climates leading to the formation of podzols with ortstein placic horizons