See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/223948755

Mineralogy and morphological properties of buried polygenetic paleosols formed in late on upland landscapes of the central plains, USA

ARTICLE in GEODERMA · JANUARY 2010 Impact Factor: 2.77 · DOI: 10.1016/j.geoderma.2009.03.015

CITATIONS READS 7 17

3 AUTHORS, INCLUDING:

Deann Ricks Presley Michel D Ransom Kansas State University Kansas State University

34 PUBLICATIONS 133 CITATIONS 29 PUBLICATIONS 593 CITATIONS

SEE PROFILE SEE PROFILE

All in-text references underlined in blue are linked to publications on ResearchGate, Available from: Deann Ricks Presley letting you access and read them immediately. Retrieved on: 02 February 2016 Geoderma 154 (2010) 508–517

Contents lists available at ScienceDirect

Geoderma

journal homepage: www.elsevier.com/locate/geoderma

Mineralogy and morphological properties of buried polygenetic paleosols formed in late quaternary sediments on upland landscapes of the central plains, USA

DeAnn Ricks Presley ⁎, Paul E. Hartley, M.D. Ransom

Kansas State University, Department of Agronomy, United States article info abstract

Article history: East central Kansas is largely comprised of alternating, level beds of Permian shale and limestone of the Received 14 August 2008 Central Plains, USA. Polygenetic upland of east central Kansas have been formed though multiple and Received in revised form 12 February 2009 likely different sets of forming factors. Upland soils in this region have a complex genesis, often contain Accepted 20 March 2009 one or more paleosols, and form in multiple parent materials including , locally reworked loess or Available online 22 April 2009 colluvium, and residuum. The depth to rarely exceeds 2 m. Upland hillslope soils commonly contain one or more paleosols, and can be observed on a variety of hillslope positions on the landscape. Generally, the Keywords: Paleosols lower paleosols are recognized by strongly expressed structure, thick continuous coatings on all faces of Mineralogy peds, and strong reddish color with either 7.5YR or 5YR hues. Soil textures of the paleosols often feel less Landscapes clayey than the overlying horizons in field determinations. At first, this was attributed to a decrease in clay Loess content, stickiness, and plasticity. However, subsequent laboratory characterization revealed that the clay Quaternary content was usually highest in the lower paleosol horizons, and that the clay mineralogy of the modern soil Great Plains was dominated by smectite, while the paleosols contained a mixed suite of minerals. Therefore, the perceived Central Plains decrease in clay content was caused by a change in clay mineralogy, a feature that can be exploited in future field descriptions in order to more accurately distinguish between stratigraphic units in these thin, welded polygenetic soils. The age of the paleosols sampled in this study were typical for the late Quaternary-aged Severance formation, clustering in two age ranges, which were ≈19,000 to 20,000 and ≈22,500 to 27,700 uncalibrated 14C yr BP. The results from this study illustrate that although they might be thin, truncated, and welded, late Quaternary-aged loess-derived soils and paleosols occur in regular, predictable patterns on many upland hillslopes in the Bluestem Hills Major Land Resource Area, and this region should be included in future regional investigations of the Central Plains. Published by Elsevier B.V.

1. Introduction other adjacent areas of the Central Plains. Although loess was likely deposited in this region, it is generally held that most of the loess has The Bluestem Hills (Fig. 1) are underlain by alternating, level beds eroded from the upland hillslopes. of Permian shale and limestone, some of which are quite cherty. Loess–paleosol sequences of the Quaternary Period are present Differential of the shale and limestone features has throughout much of the plains. Loess units widely recognized in the created a repeating bench-and-slope topography, and as such, Central Plains include the Loveland (deposited approximately relatively stable landforms exist up and down the larger, steep 500,000 to 100,00 yr BP), Gilman Canyon Formation (deposited hillslopes. Upland soils in the Bluestem Hills Major Land Resource Area approximately 41,000 to 20,000 yr BP), and Peoria Loess (deposited (MLRA 76) are thought to have a long and complex genesis, to contain approximately 25,000 to 11,000 yr BP). Frye and Leonard (1952) multiple parent materials, and to have formed under tallgrass prairie estimated that one-third of Kansas has Peoria loess at the surface. in an area that is transitional between udic and ustic moisture Later, Welch and Hale (1987) used a combination of sources including regimes. Parent materials were historically described as clayey geologic maps and county soil surveys to estimate that approximately sediments, such as residuum, although recent investigations have 65% of the state was covered with loess. According to described a more complicated and polygenetic suite of parent Welch and Hale (1987), widespread loess deposits are not recognized materials for the modern soil and underlying paleosols (Wehmueller, in east-central and southeastern Kansas, which includes the southern 1996; Glaze, 1998). Thick loess deposits (N2 m) are not recognized in two-thirds of the Bluestem Hills MLRA. this portion of Kansas, although thicker loess units are recognized in On upland landscapes in east central Kansas, including the study area, buried paleosols with preserved A horizons are rare. It is much fi ⁎ Corresponding author. Fax: +1 785 532 6315. more common to nd the modern soil superimposed (e.g.,welded) E-mail address: [email protected] (D.R. Presley). almost seamlessly onto the Bt horizon of one (or more than one)

0016-7061/$ – see front matter. Published by Elsevier B.V. doi:10.1016/j.geoderma.2009.03.015 D.R. Presley et al. / Geoderma 154 (2010) 508–517 509

Fig. 1. Location of Bluestem Hills Major Land Resource Area in Kansas, and example of the landscape and vegetation of the study area. paleosol. Also, it is common to see a dark red soil that is located above contain two paleosols. In addition, these upland soils occur on hillslope bedrock, and beneath the upper material (loess). This red paleosol locations across the landscape and can be recognized by subtle sharply contacts interbedded Permian limestones and shales, and is differences in morphology as well as differences in mineralogical commonly regarded by soil scientists as being derived mostly from composition. Therefore, the objective of this study was to use residuum from these bedrock members. The soil matrix is often dark morphology as well as laboratory characterization including mineralogy red in color with hues of 5YR or 7.5YR (or redder) and values and to identify the stratigraphy and features of soil development within chromas of 4 or less. This material is very clayey and dense, with polygenetic soil profiles that are mapped on hillslopes. The secondary strongly expressed structure, thick clay films, and fragments that objectives were to confirm field observations of paleosols and subtle may or may not be similar to the underlying bedrock. Many soil differences noticed between paleosols, which are often difficult to scientists agree that this is a paleosol, but differ in opinions as to the distinguish in thin loess-derived soils due to welding of the thin units via parent material and age of the paleosol and/or sediments. (Jacobs and Mason, 2007; Johnson et al., 2007), and to We hypothesize that although the upland soils of east central Kansas relate these thin, predominately loess-derived soils to the current body lack buried A horizons that are preserved, they are polygenetic and often of knowledge on Great Plains loess and paleosol sequences. 510 D.R. Presley et al. / Geoderma 154 (2010) 508–517

2. Site and methods (containing 30 mg of clay) were pipetted onto a glass slide. A Phillips XRG-3100 generator and an APD 3520 X-Ray diffractometer was used 2.1. Geographic setting and site location to analyze all samples. The clay specimens were scanned from 2°2θ to 34°2s for the Mg 25 °C treatment, and from 2°2θ to 15°2θ for the other The study area is located in the lower Cottonwood River watershed treatments. The silt samples were scanned from 18°2θ to 54°2θ using in the Bluestem Hills Major Land Resource Area in eastern Chase powder diffraction specimen holders. The d-spacing of each peak was County, Kansas (Fig. 1). Land use for all sampled pedons is either determined using the table on p. 224 of Jackson (1975), and the clay native range or land that is in hay pastures. In this physiographic minerals were subsequently identified. region, the shallow nature of the soil profiles makes it unsuitable for cultivation. However, some land was cultivated for a brief period 2.5. Numerical dating and stable isotope analysis during the mid twentieth century and then planted to grass for hay production. Sampling locations A, B, and C were in native range Five horizons (one per pedon) were selected for numerical dating pastures, and D was in a formerly cultivated hay pasture. Predominant of paleosols. Samples were analyzed by the Illinois Geological Survey vegetation types are listed in Table 1. Annual precipitation is 785 to Isotope Geochemistry Laboratory. Samples were processed, purified 965 mm (USDA-NRCS, 2006). and collected by cryogenic distillation for accelerator mass spectro- metry (AMS) 14C and δ13C analyses (Hong Wang, personal commu- 2.2. Field description and sampling nication). Stable carbon isotope values (‰) are reported relative to a standard reference material, the Peedee belemnite (PDB) standard Nineteen soil pedons were sampled from four hillslope positions. (Faure, 1998). All pedons were described using the Field Book for Describing and Sampling Soils (Schoeneberger et al., 2002). Five representative 3. Results and discussion pedons (i.e., representative of the soils mapped on these hillslope positions) were selected for laboratory characterization, isotopic 3.1. Soil characterization analysis, and numerical dating. Bulk samples were collected from the horizons of all selected pedons for laboratory characterization and Of the 19 pedons that were described, five were selected for thick horizons (N20 cm) were split and sub-sampled. Four of these detailed investigation, one from each general sampling area (A, B, and pedons were chosen for mineralogical analysis. From these four D) and two pedons from site C (Fig. 1 and Table 1). A summary of field pedons, three horizons (per pedon) were selected for clay miner- descriptions for the five characterized pedons is presented in Table 2. alogical analysis using X-ray diffraction spectrometry. Physical and chemical characterization data are given in Table 3. All pedons are arranged in order of the highest to the lowest elevation. 2.3. Laboratory characterization 3.1.1. Morphology and stratigraphy: evidence for multiple stages of Air-dry bulk samples were crushed with a wooden rolling pin and pedogenesis passed through a No. 10 sieve with 2 mm square openings. Soil pH was All pedons were sampled from upland landscape positions determined in a 1:1 soil/water suspension using method 8C1F of the described as hillslopes primarily ranging from 1 to 2% slope, and up Laboratory Staff (1996).Totalcarbon(TOC)was to 4% for pedon C1 (Table 1). Note that the hillslope designation determined using a high-frequency induction furnace (Leco Model reflects the microtopgraphy of the landscape, which is composed of CNS-2000, St. Joseph, MI) following the procedure of Tabatabai and many, complex slopes. Despite being located on upland hillslopes, the Bremner (1970). Particle size distribution was determined using a pedons exhibited morphological features indicative of stable land- modification of the pipet method of Kilmer and Alexander (1949) and forms. Table 2 contains information about the parent material method 3A1 from the Soil Survey Laboratory Method Manual (1996). stratigraphy, horizonation, matrix color, and clay film morphology as Organic matter was removed from samples with 30% hydrogen described in the field. At all of the sampling locations, a paleosol, peroxide. Cation exchange capacity (CEC) and base saturation % were which was welded to the modern soil, occurred at a depth of determined by summing the NH4OAc extractable bases and the BaCl2- approximately 0.8 to 1 m. A second, more strongly expressed paleosol TEA extractable acidity (method 5A3a of the Soil Survey Laboratory was observed in all sampling locations deeper in the soil profile Staff (1996). Exchangeable sodium percentage (ESP) was determined (Table 2), except for pedon D, where only one paleosol was recognized by dividing the exchangeable sodium by the sum of cations CEC. in the field investigation. Criteria for recognition of a paleosol included differences in 2.4. Mineralogy structure, color, clay coating morphology, and field textures (Wang and Arnold, 1973). Moderate, medium, prismatic structure was Total silt and clay mineralogy was analyzed following the methods commonly observed in the modern soil, and moderate fine or medium of Jackson (1975). Samples were pretreated with 1 M NaOAc and 30% subangular blocky dominated both paleosols. The modern soil was

H2O2 to remove carbonates and organic matter, respectively. Silt and described with 10YR mollic colors in the epipedon, and commonly as clay were fractioned through at least eight sedimentation periods. Five 10YR4/3 in the lower portion. Hues of 7.5YR or 5YR were observed in clay treatments were prepared: Mg 25 °C, Mg-ethylene glycol the paleosols, and the color of the residuum varied depending on the solvation, K 25 °C, K 350 °C, and K 550 °C. Two milliliters of solution bedrock (commonly gray or green colors for non-calcareous shale, and

Table 1 Site characteristics of characterized pedons.

Pedon Elevation (m) Slope (%) Aspect Hillslope position Slope shapea Vegetation Taxonomic classification A 382 2 225 Backslope LC Andropogon gerardii, Sorghastrum nutans, Panicum virgatum Fine, smectitic, mesic Pachic Argiustoll B 376 2 180 Backslope LL Andropogon gerardii, Sorghastrum nutans, Panicum virgatum Fine, smectitic, mesic Pachic Argiustoll C1 368 4 270 Backslope LL Andropogon gerardii, Sorghastrum nutans, Panicum virgatum Fine, smectitic, mesic Pachic Paleustoll C2 368 1 270 Shoulder LL Andropogon gerardii, Sorghastrum nutans, Panicum virgatum Fine, smectitic, mesic Pachic Argiustoll D 358 2 158 Footslope LC Bromus inermis Fine, smectitic, mesic Typic Argiustolls

a LL — linear–linear, LC — linear–concave. D.R. Presley et al. / Geoderma 154 (2010) 508–517 511

Table 2 Selected field morphological properties of characterized pedons.

Soil horizon Depth (cm) Matrix colora Structureb Stickinessc Plasticityd Ped surface featurese Concentrationsf % N2mm Pedon A A1 0–14 10YR2/1 1 f sbk ms mp A2 14–22 10YR2/2 2 f sbk vs vp Bt1 22–55 10YR3/2 2 m pr vs vp 5 f d Bt2 55–71 10YR3/3 2 m pr vs vp 5 f d Bt3 71–89 10YR4/3 2 m pr vs vp 2 f d 1 Btk1 89–116 7.5YR4/4 2 m pr vs vp 1 f d 2 m can 1 2Btk2 116–143 7.5YR3/3 2 f sbk vs vp 10 f d 1 f cam 1 3Bt1 143–169 5YR3/3 2 f sbk ms ms 25 f c 1 3Bt2 169–180 10YR5/4 1 f sbk ms mp 5 4Cr 180–200+ Weathered calcareous shale

Pedon B A0–7 10YR2/1 1 f sbk ss sp BA 7–14 10YR2/1 2 f sbk ms mp Bt1 14–35 10YR3/2 2 m pr vs vp 5 f p Bt2 35–51 10YR3/3 2 m pr vs vp 5 f p Btk 51–73 10YR4/3 2 m sbk vs vp 5 f p 20 f can Bt1’ 73–83 10YR4/3 2 m sbk vs vp 5 f p 2Bt2 83–99 7.5YR4/3 2 m sbk vs vp 25 f c 2 3Bt3 99–138 7.5YR3/3 2 m sbk ms mp 50 f c – 4Cr 138–143+ 10YR5/4 Weathered non-calcareous shale

Pedon C1 A0–20 10YR2/1 1 f sbk ss sp Bt1 20–33 10YR2/2 2 m pr vs vp 5 f d Bt2 33–52 10YR3/2 2 m pr vs vp 5 f d 1 Bt3 52–69 10YR3/4 2 m pr vs vp 5 f d 2 Btky 69–108 10YR4/3 2 m pr vs vp 10 f d 2 f can 5 2 f gym 2Bt 108–148 7.5YR3/3 2 m sbk vs vp 25 f c 2 3CB 148–167 2.5YR5/3 1 m sbk ms mp 80 7.5YR3/3 3C 167–189 5Y5/2 0 ma ms mp 80 4Cr 189–207+ 5Y5/2 Weathered non-calcareous shale

Pedon C2 A0–19 10YR2/1 1 f sbk ss sp 1 Bt1 19–30 10YR2/1 2 f sbk vs vp 5 f d 1 Bt2 30–57 10YR2/2 2 m pr vs vp 5 f d 1 Bt3 57–72 10YR3/4 2 m pr vs vp 5 f d 1 Btk 72–92 7.5YR4/3 2 m pr vs vp 5 f d 2 m can 1 2Btky 92–126 7.5YR3/3 2 m pr vs vp 10 f d 1 f can 5 1 f gym 3Bt1 126–175 7.5YR3/2 2 f sbk ms mp 25 f c 5 3Bt2 175–222 7.5YR2.5/2 2 f sbk ms mp 50 f c 5 4C 222–237 5Y5/2 0 ma vs vp 50 5Cr 237–250+ 10YR5/6 Weathered limestone

Pedon D A0–17 10YR2/1 2 f gr ss sp BA 17–26 10YR2/2 2 f sbk ms mp Bt1 26–41 10YR3/2 2 m sbk vs vp 20 f d Bt2 41–55 10YR4/2 2 f pr vs vp 10 f d Bt3 55–77 10YR4/3 2 m pr vs vp 8 f d 1 Bt4 77–100 10YR4/3 2 f pr vs vp 2 f p 1 2Btg1 100–165 2.5Y5/2 2 m pr vs vp 10 f d 2 2Btg2 165–200 2.5Y5/2 2 m pr vs vp 5 f d 2 2Btg3 200–206+ 2.5Y6/2 2 m pr vs vp 5 f d 10

a Moist color of broken ped faces. b Grade — size-type. c ss — slightly sticky, ms — moderately sticky, vs — very sticky. d sp — slightly plastic, mp — moderately plastic, vp — very plastic. e Abundance (%), contrast, continuity. f Abundance (%), size, type, can — carbonate nodules, cam — carbonate masses, gym — gypsum masses. tan for limestone or calcareous shale). Clay coatings were less the clay content. This transition was interpreted as a change in abundant and either patchy or discontinuous in the modern soil, stratigraphy, with the gray color resulting from iron depletion. Many and more abundant and continuous, coating all faces of peds in the gray, non-calcareous shales occur in this area, but abundant reddish- paleosols. colored redoximorphic concentrations were also observed. Therefore, An exception to these trends, namely the color criteria, occurred in the “g” subscript was added to the horizon nomenclature. Clay films pedon D. At a depth of 100 cm, a color transition from 10YR4/3 to were present on ped faces, so the horizons were designated with 2Btg 2.5Y5/2 occurred quite abruptly in pedon D, along with an increase in notation. Since no additional changes in stratigraphy were observed 512 D.R. Presley et al. / Geoderma 154 (2010) 508–517

Table 3 paleosol horizons. However, the field textures were described as silty Selected physical and chemical properties of characterized pedons. clay or clay, so the parent material was termed reworked loess. In Soil Depth Sand Silt Clay FC: pH TOC BS ESP pedons A, B, and C2 the stratigraphy was interpreted as follows: loess horizonsa (cm) (%) (%) (%) TCb (%)c (%)d (%)e over reworked loess (upper paleosol), over reworked loess (lower Pedon A paleosol), over residuum weathered from limestone and shale A1 0–14 3.5 71.1 25.4 0.62 5.8 2.47 81.3 2.1 (example shown in Fig. 2). Pedon C1 was thought to contain loess – A2 14 22 3.1 58.7 38.2 0.65 6.4 1.43 92.9 5.7 over reworked loess (upper paleosol), over two units of residuum. Bt1 22–40 1.7 49.4 48.9 0.68 7.0 1.13 85.8 5.6 Bt1 40–55 1.2 53.3 45.5 0.65 7.3 0.98 92.2 7.2 Pedon D was described with loess over reworked loess (paleosol) to a Bt2 55–71 1.5 53.4 45.1 0.67 7.6 0.78 89.9 8.1 depth of over two meters. Between 83 cm (pedon B) and 116 cm Bt3 71–89 2.4 56.7 40.9 0.62 7.3 0.45 92.0 8.0 (pedon D) of loess was described on the upland positions, and 142 cm Btk1 89–116 3.4 56.7 39.9 0.58 7.7 0.32 85.8 7.8 of loess was described on the lowest hillslope position examined in 2Btk2 116–143 4.2 52.6 43.2 0.60 6.8 0.37 83.8 8.2 this study (pedon D). 3Bt1 143–169 4.5 37.5 58.0 0.72 7.4 0.43 86.8 8.3 3Bt2 169–180 2.1 44.8 53.1 0.60 nd nd nd nd 4Cr 180–200+ nd nd nd nd nd nd nd nd 3.1.2. Physical and chemical properties

Pedon B 3.1.2.1. Particle size analysis. Despite having differences in thickness A0–7 2.8 67.2 30.0 0.67 7.7 4.78 68.1 0.9 BA 7–14 2.3 589 38.8 0.73 7.8 2.13 64.6 1.6 of the solum, and individual parent materials, all of the pedons have a Bt1 14–35 1.8 53.2 45.0 0.68 7.1 1.34 82.6 3.9 similar distribution of the clay content with depth (Table 3). All of the Bt2 35–51 2.2 54.5 43.3 0.66 7.6 1.08 85.3 7.0 pedons had two clay maxima, one at a depth of approximately 25– Btk 51–73 3.3 53.3 43.4 0.67 7.8 0.86 81.0 7.6 50 cm, and one much deeper in the profile (N1 m). Pedons A, B, C1, and Bt1’ 73–83 2.8 51.7 45.5 0.69 nd 0.52 92.8 10.5 C2 contained less than 5% sand in the profile, and the sand content of 2Bt2 83–99 2.2 50.2 47.6 0.67 7.4 0.39 87.0 11.5 3Bt3 99–138 2.0 49.4 48.6 0.72 7.3 0.49 82.2 10.7 pedon D was not greater than 8%. The particle size distribution of all 4Cr 138–143+ nd nd nd nd nd nd nd nd horizons sampled was bi-modal (Fig. 3) with large quantities of coarse silt (50 to 20 µm), to medium silt (20 to 5 µm) and clay (b2 µm). Pedon C1 Mason et al. (2003) found problems with using mean particle size for A0–20 3.0 73.6 23.4 0.56 6.4 2.05 59.2 2.5 Bt1 20–33 3.1 53.7 43.2 0.66 6.7 1.35 67.2 4.2 wind strength when they observed sedimentary aggregates in C Bt2 33–52 2.8 52.1 45.1 0.62 7.2 1.15 82.8 5.9 horizons of Peoria loess in Nebraska. In thin section, non-pedogenic Bt3 52–69 2.7 53.0 44.3 0.61 nd 0.81 86.1 7.3 clay coatings were present on silt and sand grains. Aggregates were Btky 69–90 3.8 54.0 42.2 0.63 nd 0.40 93.9 8.4 also visible in thin section. Muhs et al. (1999) observed bi-modal – Btky 90 108 3.5 50.2 46.3 0.66 7.7 0.28 75.5 7.0 distributions in studies of clayey loess in eastern Colorado, with peaks 2Bt 108–130 3.4 46.2 50.4 0.68 7.5 0.28 86.5 7.6 – b 2Bt 130–148 2.6 47.0 50.4 0.65 7.4 0.18 78.4 6.7 in the 20 30 µm range, and in the 4 µm clay-size fraction, and 3CB 148–167 0.9 58.7 40.4 0.55 7.9 0.10 71.2 6.0 attributed this to either a local, clayey source such as the Pierre shale, 3C 167–189 0.3 57.6 42.1 0.45 7.9 0.13 88.2 6.7 or silt-sized clay aggregates (Muhs et al., 1999). – 4Cr 189 207+ nd nd nd nd nd nd nd nd In pedon A, the particle size distribution of the Bt1 (40–55 cm,

Pedon C2 modern soil) was very similar to the distribution of the 2Btk2 horizon A0–19 4.0 65.4 30.6 nd 5.9 2.30 nd nd (116–143 cm, upper paleosol). The 3Bt2 horizon (169–180 cm, lower Bt1 19–30 2.9 56.5 40.6 nd 6.2 1.32 nd nd paleosol) had a lower coarse silt % and higher coarse and fine clay %, as Bt2 30–46 2.8 55.4 41.8 nd 6.9 1.07 nd nd well as a higher fine clay to total clay ratio, FC:TC (Table 3). Due to the – Bt2 46 57 2.6 56.0 41.3 nd 7.5 0.88 nd nd previously mentioned differences in morphology, and particle size Bt3 57–72 nd nd nd nd nd nd nd nd Btk 72–92 3.2 56.8 40.0 nd 7.6 0.57 nd nd distribution, two paleosols were described in pedon A. 2Btky 92–126 2.5 56.9 40.6 nd 7.4 0.38 nd nd 3Bt1 126–154 2.6 51.6 45.7 nd 7.6 0.45 nd nd 3Bt1 154–175ndndndndndndndnd 3Bt2 175–222+ 2.0 51.3 46.7 nd 8.2 0.37 nd nd

Pedon D A0–17 5.5 68.3 26.2 0.50 5.9 2.50 64.7 0.0 BA 17–26 4.7 60.9 34.4 0.63 nd 1.61 62.2 0.5 Bt1 26–41 3.6 55.2 41.9 0.69 5.7 1.10 73.2 1.5 Bt2 41–55 4.8 55.7 39.5 0.71 5.7 0.77 77.9 2.4 Bt3 55–77 5.3 58.4 36.3 0.71 6.8 0.54 82.8 4.1 Bt4 77–100 5.7 54.9 39.4 0.72 7.4 0.28 90.3 7.2 2Btg1 100–130 3.5 39.4 57.1 0.82 7.6 0.22 93.0 9.7 2Btg1 130–165 4.6 45.4 50.0 0.80 7.8 0.10 94.2 11.2 2Btg2 165–200 6.4 50.0 43.6 0.76 7.7 0.06 95.6 11.8 2Btg3 200–206+ 7.8 52.3 39.9 0.75 nd 0.05 90.5 10.6

a Thick horizons (N≈40 cm) were split for chemical and physical analyses. b FC:TC — fine clay:total clay. c TOC — total organic carbon. d BS — base saturation. e ESP — exchangeable sodium percentage. within the sampling depth (206 cm), the presence of only one paleosol was recognized in pedon D. It was debated whether this site was an upland footslope of the Bluestem Hills, or a paleoterrace of the present-day Cottonwood River. Due to the silty textures and lack of coarse (N2 mm) fragments, the Fig. 2. Image of Pedon B, sampled using a hydraulic soil probe. All pedons were sampled upper portion of all pedons was called loess (Table 1). A few coarse from native, grazed pastures. A radiocarbon date of 24,490±120 14C yr BP, and a δ13C fragments ranging from 2 to 10 mm-diameter were present in the value of −16.9‰ was obtained for the 3Bt3 horizon (99–143 cm). D.R. Presley et al. / Geoderma 154 (2010) 508–517 513

Fig. 3. Stratigraphy, 14C dating, and δ13C values.

In pedon B, the particle size distribution of the Bt2 horizon of the increasing slightly in the lower paleosols of pedons A, B, and C1. As modern soil (35–51 cm) was different than the distribution of the two previously mentioned, no distinct, former surface horizons are paleosol horizons (2Bt2 and 3Bt3), which were similar to each other preserved in these soils. Rather, it is thought that the paleosols were (83–99 and 99–138 cm, respectively). Despite having differences in truncated and later became welded to the modern soil profile. In the abundance of clay films (25% in the 2Bt2 horizon, and 50% in the previous studies, Wehmueller (1996), Glaze (1998), and Gunal and 3Bt3 horizon), the particle size distribution does not support the Ransom (2006) observed clay coatings that superimposed carbonate concept of two paleosols in pedon B. The abundance of clay films, as features in thin sections as well as higher FC:TC in paleosols, indicative well as the FC:TC is greater for the 3Bt3 horizon. Therefore, it is of clay illuviation from the modern soil into the paleosol horizons. possible that the two horizons may actually be different horizons of The exchangeable sodium % (ESP) values of all five pedons ranged the same paleosol, and thus this shallow pedon (138 cm to residuum) from 0 to 2.5% in the surface horizons, and increase with depth. Quite might only contain one paleosol. often, values are greater for shallower pedons, such as pedon B. Glaze Both pedons C1 and D have particle size distributions that appear (1998) concluded that Permian sedimentary bedrock was the likely to be unique for each of the three horizons analyzed. In pedon C1, the source for the elevated Na+, and Presley (2007) hypothesized that modern soil (Bt2, 33–52 cm) and upper paleosol (2Bt, 108–130 cm) particles of local dust weathered from these Permian rocks may have contain large quantities of coarse silt and fine clay, while the 3CB been incorporated during deposition of the loess and/or with horizon (148–167 cm) contains an abundance of fine silt and a colluviation in the late Quaternary period. relatively lower quantity of fine clay. However, these data support the horizon nomenclature of all three horizons sampled from the C1 3.2. Mineralogy pedon. The FC:TC for the argillic horizons were 0.62 and 0.68 for the Bt2 and 2Bt horizons, respectively (Table 3), and they were both 3.2.1. Identification and distribution of silt and clay minerals described in the field as containing 5% and 25% clay coatings (Table 2). The total silt fractions of all horizons were dominated by quartz, The 3CB horizon lacked clay coatings and had a FC:TC of 0.55. Pedon D and contained lesser amounts of plagioclase and K-feldspars (Table 4). has the most differences between the three selected horizons. The Bt2 Calcite was observed in the silt fraction of three samples, though not in horizon of the modern soil (41–55 cm) contains the most coarse silt any horizons described in the field as containing carbonate nodules or and the least fine clay, the upper part of the paleosol (upper portion of masses. Gypsum was not observed in any silt or clay despite being 2Btg1,100–130 cm) is intermediate, and the lower part of the paleosol observed in the field at a depth of 92–126 cm in Pedon C2. (2Btg2, 165–200) contains the least coarse silt and a great deal more Total clay mineralogy is displayed in Fig. 4 for the Mg-25 and Mg- fine clay than the other horizons. Therefore, despite the similarity in EG treatments. Additional treatments including K-25, K-350, K-550, field described properties, particle size data differs for the two and Mg-glycerol solvated were analyzed. These data are not shown, paleosol horizons. but the results are available in Presley (2007). One of the greatest and most consistent within-profile differences 3.1.2.2. Chemical properties. Selected characterization data for is that in pedons A, B, and C2, the modern soil contains greater chemical properties are shown in Table 3. Surface horizons of pedons quantities of smectite and only trace amounts of vermiculite, while A, C1, C2 and D were similar with pH values ranging from 5.8 to 6.4 the upper and lower paleosol horizons analyzed contained approxi- and total carbon (TC) values between 2 to 2.5%. Pedon B had a higher mately equal abundances of smectite and vermiculite (Fig. 4). In surface horizon pH (7.7), which might be attributed to its shallower contrast, pedon D is the opposite as the modern soil contains depth, both overall (138 cm to residuum) and for the modern soil in considerably less smectite when compared with the paleosol particular (83 cm). Pedon B also contained greater TC (4.78%). horizons. Clay mica or illite content varies both within pedons, and However, this value is extremely high for eastern Kansas, so one between all pedons. In pedon A, illite is most abundant in the paleosol explanation might be that some surface litter was mixed with the horizons, constituting approximately 30% of the total clay fraction. The pedon B surface sample prior to TC analysis, or another possibility is illite content is generally greater for pedon A than B for all horizons. that this pedon was actually less eroded than the other pedons in the Pedon C2, however, contains a large quantity of illite in all horizons, study. Total C values decrease regularly with depth in all pedons, but like pedon A, the illite content increases with depth, and in nearly 514 D.R. Presley et al. / Geoderma 154 (2010) 508–517

Table 4 in the lower paleosol (3Bt2, 175–222 cm). The kaolinite content of the Semi-quantitative mineralogy for total silt fraction (2000–50 µm). 3Bt2 horizon of pedon C2 is similar to that of the other horizons Horizon Depth Quartz Plagioclase Potassium Calcite analyzed from pedons A, B, and D. (cm) feldspars feldspars In field descriptions, the clay content of the paleosols of pedons A, Pedon A B, and C2 was estimated to decrease by 8 to 10% relative to the Bt1 40–55 XXXa XXndoverlying modern soil, and to decrease in stickiness and plasticity. – 2Btk2 116 143 XXX X X nd However, particle size determination indicated that the clay content 3Bt2 169–180 XXX X nd XX was greater for the paleosols. The likely explanation for these three Pedon B pedons, sampled in this study area, is the change in mineralogy class. Bt2 35–51 XXX X X nd The modern soil of pedons A, B, and C2 is dominated by smectite, and 2Bt2 83–99 XXX X X X the paleosols exhibit a more mixed mineralogy. Therefore, in addition 3Bt3 99–138 XXX X X nd to changes in color, clay film morphology, and structure, stickiness and Pedon C2 plasticity differences may potentially be utilized to differentiate Bt2 46–57 XXX X X X paleosols from modern soils in field investigations. However, these 2Btky 92–126 XXX X X nd differences must be evaluated with subsequent laboratory analyses to – 3Bt2 175 222 XXX X nd verify the field observations.

Pedon D Bt2 41–55 XXX X X nd 3.2.2. Possible origin of clay minerals and explanations for differences 2Btg1 (upper) 100–130 XXX X X nd between modern soil, paleosols, and across hillslope positions 2Btg2 165–200 XXX XX nd nd Possible explanations for differences in clay mineralogy, both a Rating system used is nd = none detected, X = trace, XX=5–10%, and XXX=N75%. within and between profiles, include neo-formation of clay minerals (Allen and Hajek, 1989), additions from dust fall, sequential weath- ering of clay minerals, or inheritance from parent materials. The neo- identical quantities for both paleosols. Like pedon B, pedon D contains formation hypothesis is rejected due to the high pH, abundant bases, a relatively low abundance of illite for all samples (Fig. 5). and well-drained conditions present in the modern soils and paleosols In pedons A, B, and D, the kaolinite content appears constant with alike of pedon A, B, and C2. High Si, Al, Mg, and restricted drainage are depth in the horizons analyzed, and the total abundance is estimated required for neo-formation (Borchardt, 1989), therefore, this is a to be approximately 10% in all horizons of these pedons. The kaolinite potential explanation for the increased smectite content of both content of pedon C2 appears to vary slightly with depth, with larger paleosols of pedon D (Fig. 4), sampled at the lowest elevation (Table 1), quantities present in the modern soil (Bt2, 30–57 cm) and upper in a topographically lower landscape position, and containing gleyed paleosol (2Btky, 92–126 cm) horizons, and slightly lower abundance matrix horizons (Table 2). However, the pH of the paleosols exceeds 7.6

Fig. 4. Particle size distribution of selected pedons. D.R. Presley et al. / Geoderma 154 (2010) 508–517 515

Fig. 5. X-ray diffractograms of the clay (b2 µm) fraction from 2° to 34° 2Θ for Mg saturated samples (lower set of spectra) and 2° to 15° 2Θ for Mg saturated and ethylene glycol solvated samples (upper set of spectra).

(Table 3), so the neo-formation hypothesis does not adequately deposits of Kansas, Gunal and Ransom (2006) observed smectite in C explain the high smectite content in the paleosols of pedon D. horizons, and it was similar in abundance to the overlying soil and Concerning dust deposition as a possible explanation, Twiss (1983) paleosol. Therefore, the authors reasoned that the smectite was likely observed modern dust deposition in Kansas. Roberts et al. (2003) used inherited from the parent material (Peoria loess). optically stimulated luminescence (OSL) dating and found that mass The horizons in this study that contain large quantities of illite (the accumulation rates of dust (loess) were extremely high at certain paleosols) contain more evidence of pedogenesis (stronger illuvial times in the late Pleistocene in Nebraska. It seems likely that much of clay film morphology and larger FC:TC) than those with lower illite the same material was probably available as a source to the Bluestem and higher smectite content (the modern soils). Although it seems Hills of Kansas. However, if dust deposition was the explanation, the contradictory to have the most evidence of illuviation in the horizons modern soils would be expected to be relatively enriched in primary (paleosols) that contained the least weathered suite of minerals, that minerals such as feldspars and illite as compared with the paleosols, is what our data shows. Therefore, the hypothesis of inheritance from since the modern soils are constantly receiving inputs yet today. Thus, the parent materials was selected for the well-drained Pedons A, B, dust accumulation does not adequately explain differences within and C2. These trends were not applicable for pedon D, which occurred pedons. at the lowest elevation, and contained a gleyed paleosol that was If sequential weathering was the explanation, according to the enriched in smectite and fine clay relative to the modern soil. The neo- stability sequence of Jackson et al. (1952), horizons of soils with formation hypothesis is also rejected due the pH values in excess of relatively high illite content would be relatively less weathered than 7.6, so the most likely explanation selected to account for differences soils that contain large quantities of smectite. In addition, the kaolinite between the modern soil and paleosols of pedon D is also inheritance content is nearly uniform with depth and between profiles, and might from parent materials. be expected to increase in the more weathered, mature soil horizons. Therefore, the sequential weathering hypothesis is not supported for 3.3. Paleosols, radiocarbon dates, and δ13C values the soils of this study since there is no evidence for the weathering of illite to vermiculite or smectite and because the kaolinite content is Due to the sampling locations, complexity of the landscape, and relatively uniform with depth. thus, potential mixing of parent materials, the use of either radio- Therefore, the simplest and most likely explanation is that many of carbon dating or luminescence methods might not seem appropriate the features of pedons sampled across hillslope positions in east for two reasons. First, well-preserved A horizons do not exist in these central Kansas may be attributed to inheritance from parent materials, welded soils, and because they are welded, overprinting with organic namely late Quaternary loess and reworked loess. In a study of loess matter, roots, etc. is highly probable. Second, luminescence methods, 516 D.R. Presley et al. / Geoderma 154 (2010) 508–517 commonly used in loess stratigraphy projects, are probably inap- 3.3.2. δ13C values for paleosols propriate because of potential colluviation and pedoturbation. In The δ13C values were −16.8‰, −16.9‰, and −17.0‰ for the lower addition, welding may have translocated clay and silt between paleosol of pedons A, B, and C2 respectively (Fig. 3). The δ13C values stratigraphic units, further making luminescence methods inap- were −17.5‰ and −19.2‰ (PDB) for the upper paleosol of the C1 and propriate in this study of polygenetic soils. Nonetheless, in a study D pedons, respectively. During photosynthesis, green plants discrimi- of paleosols, the question is often raised, what are the ages of these nate in favor of the 12C isotope, and thus are depleted in 13C relative to soils? When were they formed, and when was the new, overlying the atmosphere (Bender, 1970). Plants that follow the C3 pathway of material deposited? Hence, radiocarbon dating of a selected set of photosynthesis (cool season grasses and trees) are more depleted in samples (five) was done to satisfy curiosity, and is presented here as 13C, and have values of δ13C that range from −23 and 34‰, with a evidence in support of our hypothesis and other morphological and mean of −27‰ (PDB). Plants that follow the C4 photosynthetic 13 mineralogical data, i.e., that these soils formed during multiple phases pathway (warm season grasses) discriminate less against CO2 than of pedogenesis. One sample was sent from each of the five pedons C3 plants, and thus are relatively less depleted than C3 plants, e.g., C4 discussed in the preceding sections. plants have values of δ13C ranging from −6to23‰, with a mean

of −13‰ (PDB) (O'Leary, 1981). Generally, C3 vegetation is associated 3.3.1. 14C values for paleosols with trees, forbs, and cool season-grasses common to cooler climates,

In pedon A, from a portion of the 3Bt1 horizon while C4 vegetation is generally found in warm, semiarid environ- (143 to 152 cm only) of the older and deeper paleosol was radiocarbon ments with high light intensity, such as grasslands and deserts. dated (Fig. 3). From pedon B, the older paleosol (3Bt3) was also dated, Studies have shown that both the proportion of C4 species and the from a depth of 99 to 138 cm. A portion of the older paleosol was also proportion of C4 biomass in a given plant community are strongly dated from pedon C2 (3Bt2, 154–175 cm only). The dates obtained related to environmental temperature (Terri and Stowe, 1976; Tieszen were as follows: 27,700±240 uncalibrated 14C yr BP for pedon C2; 24, et al., 1979; Boutton et al., 1980). Both paleosols have δ13C values that

490±120 for pedon B; and 22,490±90 for pedon A. are indicative of mixed C3–C4 vegetation, although the three values for The upper paleosol was dated from pedons C1 and D. From pedon the lower, older paleosol are both very similar and closer to a more

C1, the material dated was from the 2Bt horizon (108 to 148 cm). dominant C4 type vegetation. Relative to each other, these vegetation From pedon D, the material dated was from a portion of the 2Btg1 proxies suggest a slightly warmer and possibly drier climate was horizon (from 100–130 cm only). The age of the younger paleosol was present between 27,700 and 22,000 yr BP (and thus similar to the 20,140±70 14C yr BP in pedon C1, and 19,030±60 14C yr BP in pedon present-day climate), and a relatively cooler and possibly more moist D. Although the upper and lower paleosol horizons were not dated climate was present 20,000 to 19,000 yr BP. Mandel (2006) reported from the same pedons, it is encouraging that the upper paleosol δ13C values of −15.5 and −15.9‰ for Severance Formation samples consistently returned younger dates than the lower paleosol. There- dating to 22,620±340 and 24,560±350 14C yr BP at a location in fore, it appears that both the morphology and radiocarbon ages of Chase County, Kansas (Mandel, 2006). paleosols are reasonably consistent across the range of selected hillslope landscape positions in the study area. Published age-ranges 3.3.3. Relationships between mineralogy, paleosols, radiocarbon dates, for the Gilman Canyon Formation, based on radiocarbon and OSL and δ13C values dating, are as follows: 40,000 to 24,000 yr B.P. (Bettis et al., 2003), In the previous section, 14C values and δ13C values were different 50,000 to 30,000 yr BP (Busacca et al., 2004), 36,000 to 22,000 (Muhs for the upper and lower paleosols sampled on different hillslope et al., 1999), and 36,000 to 30,000 (Maat and Johnson, 1996). positions. Therefore, although these soils were not sampled from Karlstrom et al. (2008) recently published AMS radiocarbon dates of stable, summit landscape positions, they proved to contain a record of 30,300 to 22,400 for soils developed in the Gilman Canyon Formation pedogenesis from the late Quaternary geologic period in a geographic (loess) sampled in Kansas, from a complete late Quaternary loess- region that is largely ignored by loess researchers (Fig. 1). Despite paleosol section approximately 100 km to the northwest of the study differences in ages and potential differences in climate, no major area. Mandel and Bettis (2001, 2003) observed a deposit that was differences between the clay mineralogy of paleosols are apparent. similar in age and properties to the Gilman Canyon Formation loess in Rather, the mineralogy of the paleosols and the younger, modern soil valleys and older footslopes in northeast Kansas and named these profile contrasted more with the paleosols, and pedons A, B, C1, and C2 colluvial and alluvial facies the Severance Formation. Radiocarbon contrasted with pedon D, the topographically lowest pedon sampled ages of the Severance Formation range from 25,000 to 15,000 (Mandel in this study. and Bettis, 2003). Note that in the studies by Mandel and Bettis, their profiles contained well-preserved A horizons, making the use of radiocarbon dating much more feasible and appropriate. 4. Summary and conclusions The uncalibrated 14C dates range from 27,700 to 22,490 yr BP for the lower paleosol. These dates reflect a time when the paleosol was Field investigations of thin, loess- and reworked-loess-derived likely buried by younger material, i.e., the sediments that comprise the soils of east central Kansas revealed the potential presence of one or upper paleosol. (Thermoluminescence dating would be the best more paleosols, characterized in the field as having lower clay technique to estimate the time frame in which the sediments were contents than the overlying modern soil. Subsequent laboratory deposited). The upper paleosol, therefore, was likely buried by characterization revealed that the total clay content and FC:TC were younger sediments between approximately 20,140 to 19,030 (or usually highest in the lowest paleosol horizons. The perceived potentially younger). Due to the level of development and the decrease in clay content was actually caused by a change in clay numerical ages, the lower paleosol could have either formed in mineralogy. This trend can be exploited in future field descriptions in Loveland loess and thus represent the Sangamon paleosol, or it could order to more accurately distinguish between stratigraphic units in have formed in hillslope sediments of the Severance Formation, e.g., these thin, welded polygenetic soils. reworked Gilman Canyon Formation loess. The upper, less developed Polygenetic upland soils of east central Kansas have been formed paleosol may have also formed in a younger unit of Severance though multiple and likely different sets of soil forming factors. The Formation , i.e., reworked Gilman Canyon Formation loess, presence of two buried paleosols that occur in regular, predictable and the modern soil profile is likely formed in Peoria loess, a unit that locations on the landscape is indicative of at least three periods of is mapped on the surface across about 65% of Kansas (Welch and Hale, parent material deposition and soil formation. The age of the paleosols 1987). was typical for the late Quaternary-aged Severance Formation, D.R. Presley et al. / Geoderma 154 (2010) 508–517 517 clustering in two age ranges, which were ≈19,000 to 20,000 and Johnson, W.C., Willey, K.L., Mason, J.A., May, D.W., 2007. Stratigraphy and environmental ≈ 14 reconstruction at the middle Wisconsinan Gilman Canyon formation type locality, 22,500 to 27,700 uncalibrated CyrBP. Buzzard's Roost, southwestern Nebraska, USA. Quat. Res. 67, 474–486. Mineralogy of the modern upland soils tend to be dominated by Karlstrom, E.T., Oviatt, C.G., Ransom, M.D., 2008. Paleoenvironmental interpretation of smectite, while paleosols had a more mixed mineralogy containing multiple soil-loess sequence at Milford Reservoir, northeastern Kansas. Catena 72, 113–128. approximately equal amounts of clay mica, vermiculite, smectite, and Kilmer, V.J., Alexander, L.T., 1949. Methods of making chemical analyses of soils. Soil Sci. kaolinite. However, one pedon sampled on a long, linear-convex 68, 15–24. footslope position was opposite in that the modern soil was mixed and Maat, P.B., Johnson, W.C., 1996. Thermoluminescence and new 14C age estimates for late – the paleosols contained more than 50% smectite. Differences in Quaternary in southwestern Nebraska. Geomorphology 17, 115 128. Mandel, R.D., 2006. Geomorphology, Quaternary stratigraphy, and geoarchaeology of mineralogy between the stratigraphic units were likely inherited from Fox Creek Valley, Tallgrass Prairie National Preserve, Northeast Kansas. Kansas the parent materials. The high smectite content of the footslope pedon Geological Survey Open-File Report 2006-29. Kansas Geological Survey, University is likely from sequential weathering as the age is similar to the other of Kansas, Lawrence, KS. Mandel, R.D., Bettis III, E.A., 2001. Late Quaternary landscape evolution in the South Fork pedons. Although the stratigraphy appears similar, there could be of the Big Nemaha River valley, southeastern Nebraska and northeastern Kansas. differences in the source of the colluvium for the footslope pedon. Guidebook no 11, Conservation and Survey Division. University of Nebraska, The results from this study illustrate that although they might be Lincoln. Mandel, R.D., Bettis III, E.A., 2003. Late Quaternary landscape evolution and stratigraphy thin, truncated, and welded, late Quaternary-aged loess-derived soils in northeastern Kansas and southeastern Nebraska. In: Niemi, T.M. (Ed.), Geologic and paleosols occur in regular, predictable patterns on many upland Field Trips in the Greater Kansas City Area (Western Missouri, Northeastern Kansas, hillslopes in the Bluestem Hills Major Land Resource Area, and this and Southeastern Nebraska. Missouri Department of Natural Resources, Geological Survey and Resource Assessment Division, Guidebook for Field Trips, 37th North- region should be included in future regional investigations of Great Central Section Meeting of the Geological Society of America, Special Publication Plains loess. No. 11, Rolla, Missouri, pp. 127–176. Mason, J.A., Jacobs, P.M., Greene, R.S.B., Nettleton, W.D., 2003. Sedimentary aggregates in the Peoria loess of Nebraska, USA. Catena 53, 377–397. Acknowledgements Muhs, D.R., Alenikoff, J.N., Stafford, T.W., Kihl, R., Been, J., Mahan, S.A., Cowherd, S., 1999. Late Quaternary loess in northeastern Colorado: Part I — age and paleoclimatic Many thanks to the Kansas USDA-NRCS and three Chase County, significance. Geol. Soc. Am. Bull. 111, 1861–1875. – Kansas landowners. Thank-you to Adam Sparks for the beautiful O'Leary, M., 1981. Carbon isotope fractionation in plants. Phytochemistry 20, 553 567. Presley, D.R., 2007. Genesis and spatial distribution of upland soils in east central image of the Bluestem Hills landscape. Kansas. Ph.D. diss. Kansas State University, Manhattan. ProQuest Digital Disserta- tions. [database on-line]; available from http://www.proquest.com/ (publication References number AAT 3259326; accessed 12 August 2008). Roberts, H.M., Muhs, D.R., Wintle, A.G., Duller, G.A.T., Bettis III, E.A., 2003. Unprece- dented last-glacial mass accumulation rates determined by luminescence dating of Allen, B.L., Hajek, B.F., 1989. An introduction to soil mineralogy, In: Dixon, J.B., Weed, S.B. loess from western Nebraska. Quat. Res. 59, 411–419. (Eds.), Minerals in Soil Environments, 2nd ed. SSSA Book Ser., vol. 1. SSSA, Madison, Schoeneberger, P.J., Wysocki, D.A., Benham, E.C., Broderson, W.D. (Eds.), 2002. Field WI, pp. 199–278. book for describing and sampling soils, Version 2.0. Natural Resources Conservation Bender, M.M., 1970. Variations in the 13C/12C ratios of plants in relation to the pathway Service, National Soil Survey Center, Lincoln, NE. of photosynthetic fixation. Phytochemistry 10, 1239–1244. Soil Survey Laboratory Staff, 1996. Soil survey laboratory methods manual. Soil Survey Bettis III, E.A., Muhs, D.R., Roberts, H.M., Wintle, A.G., 2003. Last glacial loess in the Investigation Report No. 42 version 3.0. National Soil Survey Center, Lincoln, NE. conterminous USA. Quat. Sci. Rev. 22, 1907–1946. Tabatabai, M.A., Bremner, J.M., 1970. Use of the Leco automatic 70-second carbon Borchardt, G., 1989. Smectites, In: Dixon, J.B., Weed, S.B. (Eds.), Minerals in Soil analysis of soils. Soil Sci. Soc. Am. Proc. 34, 608–610. Environments, 2nd ed. SSSA Book Ser., vol. 1. SSSA, Madison, WI, pp. 675–718. Terri, J.A., Stowe, L.G., 1976. Climatic pattern and the distribution of C grasses in North Boutton, T.W., Harrison, A.T., Smith, B.N., 1980. Distribution of biomass of species 4 America. Oecologia 23, 1–12. Differing in photosynthetic pathway along an altitudinal transect in southeastern Tieszen, L.L., Senyimba, M., Imbamba, S., Troughton, J., 1979. The distribution of C and Wyoming grassland. Oecologia 45, 287–298. 3 C grasses and carbon isotope discrimination along an altitudinal and moisture Busacca, A.J., Beget, J.E., Markewick, H.W., Muhs, D.R., Lancaster, N., Sweeney, M.R., 2004. 4 gradient in Kenya. Oecologia 37, 337–350. Eolian sediments. In: Gillespie, A.R., et al. (Ed.), The Quaternary Period in the United Twiss, P.C.,1983. Dust deposition and opal in the Great Plains. Transactions of States. Developments in Quaternary Science. Elsevier, Amsterdam, pp. 275–309. the Nebraska Academy of Sciences, vol. XI, pp. 73–82 (Special Issue). Faure, G., 1998. Principles and Applications of Geochemistry, 2nd ed. Prentice Hall, New United States Department of Agriculture, Natural Resources Conservation Service, 2006. York. Land resource regions and major land resource areas of the United States, the Frye, J.C., Leonard, A.B., 1952. Pleistocene of Kansas. Bulletin 99. The University Caribbean, and the Pacific Basin. U.S. Dept. of Ag. Handbook, p. 296. of Kansas State Geological Survey of Kansas, Lawrence, Kansas. Wang, C., Arnold, R.W., 1973. Quantifying pedogenesis for soils with discontinuities. Soil Glaze, S.L., 1998. Sodium accumulation and genesis of polygenetic soils in northcentral Sci. Soc. Am. Proc. 37, 271–278. Kansas. M.S. thesis. Kansas State Univ. Manhattan. Wehmueller, W.A. 1996. Genesis and morphology of soils on the Konza Prairie Research Gunal, H., Ransom, M.D., 2006. Clay illuviation and calcium carbonate accumulation Natural Area, Riley and Geary Counties, Kansas. M.S. thesis. Kansas State Univ. along a precipitation gradient in Kansas. Catena 68, 59–69. Manhattan. Jackson, M.L., 1975. Soil chemical analysis: Advanced course. 2nd ed. Published by Welch, J.E., Hale, J.M., 1987. Pleistocene loess in Kansas — status, present problems, and author, Madison, WI. future considerations. In: Johnson, W.C. (Ed.), Quaternary Environments of Kansas. Jackson, M.L., Hseung, Y., Corey, R.B., Evans, E.J., Vanden Heuvel, R.C., 1952. Weathering Kansas Geological Survey Guidebook Series, vol. 5, pp. 67–84. sequence of clay-size minerals in soils and sediments: II. Chemical weathering of layer silicates. Soil Sci. Soc. Am. Proc. 17, 3–6. Jacobs, P.M., Mason, J.A., 2007. Late Quaternary climate change, loess sedimentation, and soil profile development in the Great Plains: a pedosedimentary model. Geol. Soc. Am. Bull. 119, 462–475.