Loveland Loess Research Articles

Age, genesis, and paleoclimatic interpretation of the Sangamon/Loveland complex in the Lower Mississippi Valley, U.S.A.

For more than a century, the Sangamon paleosol (the Sangamon) has been an integral part of geologic and pedologic investigations in the central United States, including the Upper Mississippi and Lower Missouri River Valleys. Compositional, pedologic, micromorphologic, stratigraphic, and age data indicate that the prominent reddish paleosol developed in silt-rich deposits of the Lower Mississippi Valley, from southernmost Illinois to northwestern Mississippi, represents multiple periods of soil formation, and is wholly or in part time equivalent to the Sangamon of the central United States. Thermoluminescence data, for localities where the Sangamon developed in loess, indicate that the primary period of loess deposition was from 190 to 130 ka (oxygen isotope stage, OIS6), that loess deposition continued intermittently from 130 to 74 ka (OIS5), and that deposition was wholly or in part coeval with Loveland loess deposition in the central United States. Beryllium-10, chemical, and pedologic data indicate that in the Lower Mississippi Valley: (1) the Sangamon represents a minimum time period of 60–80 k.y.; (2) there were at least two periods of soil formation, ca. 130–90 ka and 74–58 ka (OIS4); and (3) rates of weathering and pedogenesis equaled or exceeded the net loess-accumulation rate until at least 46 ka (OIS3) and resulted in development of a paleosol in the overlying basal Roxana Silt. Along a N-S transect from southern Illinois to western Mississippi, Sangamon macroscopic characteristics as well as the micromorphology, chemistry, and mineralogy, suggest a regional paleoclimate during periods of soil formation that: (1) was warm to hot, with a wider range in temperature, precipitation, and evapotranspiration than present; (2) had seasonal to decadal or longer periods of drought; and (3) had down-valley (southward) trends of increasing temperature and precipitation and decreasing seasonality and variation in annual to decadal precipitation.

Paleoenvironmental interpretation of multiple soil–loess sequence at Milford Reservoir, northeastern Kansas

Abstract A loess/soil section near the Republican River in northeastern Kansas includes three superposed soils/paleosols in at least three superposed loess units, including Peoria Loess (PL), the Gilman Canyon Formation (GCF), and Loveland Loess (LL), The GCF coincides with a composite soil with a 1.3 m thick, buried organic-rich (A) horizon that yields AMS radiocarbon ages from 30.3 to 22.4 ka (or 35.7 to 26.9 ka when calibrated) that overlies a 1.6 m oxidized B horizon complex. The B subhorizons stratigraphically and morphologically resemble the “reddish pedocomplex” described elsewhere in Kansas and Illinois that dates between about 69 and 35 ka. The upper LL yields a TL age of about 136 and 130 + 30 ka. Thus, PL, the GCF, and LL were probably deposited mainly during the late Wisconsinan, middle Wisconsinan, and Illinoian (∼ Oxygen Isotope Stages (OIS) 2, 3, and 6, or about 12 to 24, 24 to 60, and 130 to 188 ka, respectively). Soils 1, 2, and 3, then formed mainly during OIS stages 1, 3, and 5, respectively, or about 12 to 12, 60 to 60, and 73 to 130 ka. In comparison with other dated stratigraphic sections in the Great Plains, soils/paleosols have relatively simple, cumulic horizon sequences, as is typical at sites distal from principle loess source regions. Nonetheless, they record a complex pedosedimentary history that reflects climatically-driven variations in rates of sedimentation and pedogenesis. Soil 1 is an Udic Argiustoll with 21-cm A (mollic)/69-cm Bt (argillic)/60-cm Bk horizons, that formed under modern-type grassland and climate. Soil 3, the Sangamon paleosol, includes a 3-m thick, highly rubified and clay-rich argillic horizon that, based on its morphological properties, probably formed under a relatively warm, moist, equable climate and deciduous-type forest. Soil 2 coincides with the GCF, and as such is a pedolithostratigraphic unit that includes a 1.3-m mollic horizon and to 1.6-m oxidized 3Btb and 3BCb horizons. Whereas the oxidized B horizons apparently represent relatively warm, moist climatic conditions between about 65 to 35 ka, the upper cumulic (mollic) A horizons of the GCF probably formed under progressively cooling climate and grassland between about 35.7 and 26.9 (calibrated radiocarbon) ka. Estimated mean accumulation rates (MARs) of loess range from 0.12 m/k yr for the GCF to about 0.5 m/k yr for PL.

Stratigraphy and environmental reconstruction at the middle Wisconsinan Gilman Canyon formation type locality, Buzzard's Roost, southwestern Nebraska, USA

The middle Wisconsinan Gilman Canyon Formation at the Buzzard's Roost type locality in southwestern Nebraska was investigated to document the stratigraphy and to reconstruct the environmental and climate record. The Gilman Canyon Formation was subdivided into three loess units and three soils, with radiocarbon ages constraining it between about 40 ka and 25 ka. Stable carbon isotope ratios, magnetic susceptibility, and carbon content were used to define and characterize soils within both the Gilman Canyon Formation and underlying Illinoian Loveland Loess. At the height of soil development within the Gilman Canyon Formation, climate was supporting C 4-dominated grassland, with July temperatures equal to or exceeding those of today. Soil-forming intervals within the Loveland Loess, including the Sangamon Soil, also exhibited relative increases in C 4 biomass. Climate, as recorded in the Gilman Canyon Formation, is corroborated by regional proxy data. The formation accumulated during MIS 3, and concurrent soil formation coincided with a summer insolation maximum.

Middle to Late Pleistocene loess record in eastern Nebraska, USA, and implications for the unique nature of Oxygen Isotope Stage 2

New subsurface data reveal a nearly continuous stratigraphic record of Middle to Late Pleistocene loess sedimentation preserved beneath upland summits in eastern Nebraska, USA. Thickness and grain size trends, as well as pedologic evidence, indicate significant changes in loess sources, accumulation rates, and depositional environments. The newly defined Kennard Formation accumulated in the Middle Pleistocene, and may represent multiple thin increments of distal loess from nonglacial sources on the Great Plains. The overlying Loveland Loess, up to 18 m thick and deposited during Oxygen Isotope Stage 6 (OIS 6) (Illinoian glaciation), probably records the emergence of the Missouri River valley as a major glaciogenic loess source. The prominent Sangamon Geosol formed through long-term pedogenic alteration of the upper Loveland Loess during OIS 5 and 4. Thin loess of the Gilman Canyon Formation records slow loess accumulation and pedogenic alteration in OIS 3. The Peoria Loess (OIS 2) is similar in thickness to Loveland Loess, but may have accumulated more rapidly in an environment less favorable to bioturbation. More importantly, comparison of Peoria and Loveland loess thickness trends indicates much greater influx of nonglaciogenic loess from the Great Plains during OIS 2 than in OIS 6, suggesting colder and/or drier conditions in the Midcontinent during OIS 2 than in earlier glacial stages.

New insights on the loess/paleosol Quaternary stratigraphy from key sections in the U.S. Midwest

Three key Quaternary loess/paleosol sections were examined in the Missouri Valley (Iowa), Eustis Ash Pit (Nebraska), and in the Wittsburg Quarry (Arkansas) to gain insights into the sedimentation, environment and climate change of the U.S. Midwest. Four loess units are present separated by three well-developed paleosols. Crowley's Ridge Loess (Oxygen Isotope Stage (OIS) 8) is pre-Illinoian in age, and is the oldest loess unit investigated. A well-developed paleosol, interpreted as Yarmouth Soil (OIS 7), is found in this loess in all three sections. Overlying the Yarmouth Soil is Loveland Loess (OIS 6) which has been pedogenically altered by the Sangamon Soil (OIS 5). It has luvisolic properties but a more clayey pedogenic texture than modern luvisols and has no clear eluvial horizon. The overlying Roxana Silt (OIS 4) is pedogenically altered. At Wittsburg and Missouri Valley, the Farmdale Soil (OIS 3) is developed in the Roxana Silt. Based on pedogenic features, we correlate this paleosol to that developed in the Gilman Canyon Formation at Eustis. In Missouri Valley and Eustis sections, the paleosol has chernozemic properties and therefore, the gleyic features observed at Missouri Valley are interpreted as later alterations. Overlying the Farmdale Soil is the widespread Peoria Loess (OIS 2).

Temporal and environmental resolution of a buried loessal pedostratigraphic unit in Kansas and Nebraska

A loess/soil section near the Republican River in northeastern Kansas includes three superposed soils/paleosols in at least three superposed loess units, including Peoria Loess (PL), the Gilman Canyon Formation (GCF), and Loveland Loess (LL), The GCF coincides with a composite soil with a 1.3 m thick, buried organic-rich (A) horizon that yields AMS radiocarbon ages from 30.3 to 22.4 ka (or 35.7 to 26.9 ka when calibrated) that overlies a 1.6 m oxidized B horizon complex. The B subhorizons stratigraphically and morphologically resemble the “reddish pedocomplex” described elsewhere in Kansas and Illinois that dates between about 69 and 35 ka. The upper LL yields a TL age of about 136 and 130 + 30 ka. Thus, PL, the GCF, and LL were probably deposited mainly during the late Wisconsinan, middle Wisconsinan, and Illinoian (∼ Oxygen Isotope Stages (OIS) 2, 3, and 6, or about 12 to 24, 24 to 60, and 130 to 188 ka, respectively). Soils 1, 2, and 3, then formed mainly during OIS stages 1, 3, and 5, respectively, or about 12 to 12, 60 to 60, and 73 to 130 ka.In comparison with other dated stratigraphic sections in the Great Plains, soils/paleosols have relatively simple, cumulic horizon sequences, as is typical at sites distal from principle loess source regions. Nonetheless, they record a complex pedosedimentary history that reflects climatically-driven variations in rates of sedimentation and pedogenesis. Soil 1 is an Udic Argiustoll with 21-cm A (mollic)/69-cm Bt (argillic)/60-cm Bk horizons, that formed under modern-type grassland and climate. Soil 3, the Sangamon paleosol, includes a 3-m thick, highly rubified and clay-rich argillic horizon that, based on its morphological properties, probably formed under a relatively warm, moist, equable climate and deciduous-type forest. Soil 2 coincides with the GCF, and as such is a pedolithostratigraphic unit that includes a 1.3-m mollic horizon and to 1.6-m oxidized 3Btb and 3BCb horizons. Whereas the oxidized B horizons apparently represent relatively warm, moist climatic conditions between about 65 to 35 ka, the upper cumulic (mollic) A horizons of the GCF probably formed under progressively cooling climate and grassland between about 35.7 and 26.9 (calibrated radiocarbon) ka. Estimated mean accumulation rates (MARs) of loess range from 0.12 m/k yr for the GCF to about 0.5 m/k yr for PL.

Stratigraphy and chronology of Mississippi Valley loess in western Tennessee

The stratigraphy and chronology of loess deposits in the Mississippi Valley provide an important proxy record of the number and timing of glacial advances into the upper Mississippi drainage basin. The stratigraphy of loess and paleosols from two exposures in northwestern Tennessee reveals three major loess units that are correlated with the Loveland Loess, Roxana Silt, and Peoria Loess—from oldest to youngest. Detailed measurements of clay and secondary (pedogenic) iron contents suggest that the Loveland Loess may consist of multiple loess units which have been pedogenically welded to one another to form a composite Sangamon Soil. The mineralogy of the coarse silt fraction from one exposure reveals both primary mineralogical differences between the Peoria Loess and the Roxana Silt and pedogenic overprinting by the Sangamon Soil. Grain size and iron data suggest that the degree of pedogenic alteration increases from west to east, away from the loess source area, which probably reflects the role of sedimentation rate on the degree of pedogenic alteration of loess. However, only the Peoria Loess shows the expected exponential eastward decrease in thickness; the thickness of older loess units appears to be controlled more by the occurrence of localized erosion than by distance from source area. Most samples are resistant to solar resetting of the thermoluminescence signal, which, if unrecognized, could yield thermoluminescence ages that significantly underestimate the true age of the deposits. The best match between thermoluminescence age using the total bleach method and radiocarbon age of the Peoria Loess and Roxana Silt is achieved when either long durations of optical bleaching by sunlight (≥32 hr) or artificial ultraviolet (UV) light are applied to define the residual thermoluminescence level. Partial bleach analysis indicates that long-duration optical bleaching by sunlight or UV lamp bleaching does not systematically overbleach samples of Peoria Loess and Roxana Silt. Three thermoluminescence age estimates between 38 ± 4 (±1σ) and 53 ± 5 ka from the basal half of the Roxana Silt, and six age estimates between 18 ± 2 and 25 ± 3 ka from the basal half of the Peoria Loess are consistent with numerous finite radiocarbon dates from around the central Mississippi Valley. Thermoluminescence age estimates suggest that the oldest of the intra-Loveland Loess units is 127 ± 12 ka (one age) and may have been deposited during marine oxygen isotope stage 6. The younger two of these loess units were deposited between 113 ± 10 and 70 ± 6 ka (three ages). This latter age range for loess that underlies the top of the presumed Sangamon Soil is problematic because it requires that pedogenesis may have begun as late as approximately 70 ka. Moreover, loess deposited between about 120 and 70 ka suggests that the southern margin of the Laurentide ice sheet was within some part of the upper Mississippi Valley during this interval. This conflicts with some glacial geologic evidence, but it is consistent with global sea level and δ18O records of ice volume, which indicate several intervals of moderate glaciation during this time.

Geochemical Characteristics of a Loess‐Soil Sequence in Central Kansas

AbstractThis study focuses on a Barton County loess‐soil section in central Kansas in an attempt to retrieve the geochemical signature of the late Quaternary environmental change in the arid‐semiarid region and provide a data base of loess geochemical characteristics in the Great Plains. The data indicate that the elements (expressed as oxides) of the windborne fraction (<63 µm) that are easily solubilized and lost from the soil by chemical weathering and leaching are relatively sensitive to soil‐forming processes, whereas the insoluble elements of that fraction are controlled primarily by the chemical composition of the parent material. The geochemical imprint of pedogenesis superimposed on that of the loess parent material can be distinguished by comparing the magnetic susceptibility signature with the Fe2O3/Al2O3 ratio. Based on the geochemical imprint and radiometric dates (14C and thermoluminescence), the Bignell Loess (8000–5000 yr) is poorly weathered and the Brady Soil (10 000–8000 yr) is strongly weathered. The Peoria Loess (20 000–10 000 yr) has neither a traceable leaching nor weathering marker, and the Gilman Canyon pedocomplex (35 000–20 000 yr) is strongly leached. The reddish pedocomplex (70 000–35 000 yr) is the most strongly weathered, probably due to stable land surface conditions in a mild climate, and the Barton sand (92 000–70 000 yr) seems to have been subjected to a moderate weathering. Within the exposed portion of the Loveland Loess (260 000–92 000 yr), weathering indices are inversely correlated with the carbonate content and the carbonate‐rich soils were developed under warm dry environments before 92 000, around 193 000, and before 260 000 yr. The data also show that the geochemical background of Fe2O3 and Al2O3 is high in two portions of the section: from the Brady Soil to the Gilman Canyon pedocomplex and from LL1 to LL2 within the Loveland Loess. The geochemical background of Fe2O3 and Al2O3 in the loess‐soil sequence might have been dictated by that of eolian sources.

Thermoluminescence and new 14C age estimates for late quaternary loesses in southwestern Nebraska

Loess of late Quaternary age mantles most of Nebraska south of the Platte River Valley. At least five late Quaternary loesses are recognized: from oldest to youngest, one or more undifferentiated pre-Illinoian loesses, the Loveland Loess, the Gilman Canyon Loess, which exhibits a well developed soil and rests unconformably on the Sangamon soil, the Peoria Loess capped by the Brady soil, and the Bignell Loess, which is distributed discontinuously. Previous research shows that the Loveland Loess is Illinoian, the Gilman Canyon Loess and Peoria Loess are Wisconsin, and the Bignell Loess is Holocene. We present here the first thermoluminescence (TL) age estimates and new 14C ages for these late Quaternary loesses at two key sections in southwestern Nebraska, the Eustis ash pit and the Bignell Hill road cut. TL age estimates from all samples collected from Eustis ash pit and Bignell Hill were internally consistent. TL and 14C age estimates from these two sections generally agree and support previous age determinations. The TL age estimate on Loveland Loess indicates deposition at 163 ka. TL and radiocarbon age estimates indicate that Gilman Canyon Loess, believed to be deposited during the Farmdale interstade, first began to accumulate at about 40 ka: the lower part of the Gilman Canyon Loess is 36 ka at Eustis and the middle of the unit is 30 ka at Bignell Hill. The lower and upper parts of the Peoria Loess give age estimates of 24 ka and 17 ka, respectively. TL age estimates for deposition of the Bignell Loess are 9 ka near the base, in agreement with radiocarbon age estimates, and 6 ka immediately below the modern soil, substantiating its Holocene age. Comparisons of TL age estimates with δ 18O and insolation curves which show loess deposition during interglacial and interstadial as well as glacial periods, indicate that loess deposition on the Great Plains can occur under a variety of climatic conditions.

Climatic signals from loess-soil sequences in the central Great Plains, USA

Late Quaternary eolian deposits and buried soils in the central Great Plains are interpreted to reflect the fluctuation of climatic conditions under which they formed. The Loveland Loess was deposited approximately between 500 and 100 ka. Within the loess are four zones of pedogenic carbonate accumulation: after 416 ± 35 ka; before 260 ± 25 ka; around 193 ± 22 ka; and before 92 ± 7.0 ka. The pedogenic carbonate zones were probably formed under warm and dry conditions. The moderately weathered Barton sand at the Barton section and the equivalent Sandy Silt II at other sections, deposited between 92 ± 7.0 and 69 ± 6.4 ka, suggest windy, probably warm, and fluctuating moisture consitions. A reddish pedocomplex was formed from 70 to 35 ka under relatively warm and moist climatic conditions with a very low rate of loess deposition. Overlying the reddish pedocomplex is the Sandy Silt I, probably a stratigraphic equivalent to the Roxana Silt dated at 40−30 ka in the Central Lowlands. The Gilman Canyon Formation (35−20 ka), a thick cumulic loessial and organic-matter-rich pedocomplex, developed under relatively moist and probably cool conditions. The Peoria Loess was deposited at a very rapid rate under dry and cold conditions. The Brady Soil (10.5−8.5 ka) was formed under relatively warm and moist conditions. The poorly weathered Bignell Loess was deposited during the warm and dry Altithermal Period (9−5 ka).

Aminostratigraphic Correlation and Geochronology of Two Quaternary Loess Localities, Central Mississippi Valley

Amino acid epimeric (aIle/Ile) values from terrestrial molluscs are used to define and correlate three aminozones in loess sequences exposed across the central Mississippi Valley, in Arkansas and Tennessee. Three superposed aminozones are defined at Wittsburg quarry, Arkansas, primarily using aIle/Ile values from total hydrolysates of the gastropod genus Hendersonia: Peoria Loess (aIle/Ile = 0.07 ± 0.01), Roxana Silt (0.14 ± 0.02), and a third loess (0.28 ± 0.06). Loess units at Wittsburg quarry can be correlated on lithologic characteristics eastward across the Mississippi Valley to the Old River section, near Memphis, Tennessee; however, only one loess unit is fossil-bearing (Peoria Loess, aIle/Ile = 0.05) at that section. Radiocarbon analyses of charcoal from the upper Roxana Silt (ca. 26,000 to 29,000 yr old) and mollusc shell carbonate from the basal Roxana Silt (ca. 39,000 yr old) are used to calibrate amino acid epimeric data for the central Mississippi Valley. These data, applied to the apparent parabolic kinetic model of R. M. Mitterer and N. Kriausakul (1989, Quaternary Science Reviews 8, 353-357), suggest an Illinoian (>120,000 yr) age for the third loess in the central Mississippi Valley that is correlative with part of the Loveland Loess in Illinois and Iowa.

Loess accumulation and soil formation in central kansas, United States, during the past 400 000 years

AbstractBased on interpolation of thermoluminescence dates and the mean accumulation rate of 0.034 mm yr−1, four cycles of pedogenic CaCO3 accumulation are found within the Loveland Loess: 415–325 ka, 325–250 ka, 250–195 ka and 195–95 ka. The four CaCO3 peaks correspond chronologically to marine oxygen isotope stages 11, 9, 7 and 5, respectively. The early Wisconsin (95–70 ka) was characterized by sand dune activity. The reddish pedocomplex was formed from 70 to 35 ka under relatively warm and moist climatic conditions with a very slow rate of silt accumulation (0·016 mm yr−1). The Gilman Canyon pedocomplex, enriched in organic matter and dated at 35–20 ka, was formed under a strong physical weathering regime and a relatively high rate of silt accumulation (0·15 mm yr−1), indicating a windy, relatively moist, probably cool environment. It developed when the Laurentide ice sheet was advancing and dust content in Greenland ice core was low. The Peoria Loess was accumulated at a rate of 0·3 mm yr−1 in central Kansas under cold dry conditions when the ice sheet fluctuated around its maximum position and the dust content in the Greenland ice core was the highest. Even the warm substage around 13 ka has some corresponding evidence in the central Great Plains. The well‐developed Brady Soil, dated at 10·5–8·5 ka, indicates that the early Holocene was the optimal time for soil development since 20 ka. The poorly weathered Bignell Loess might have been deposited during the Altithermal Period from 8·5 to 6 ka.

Chronologic evidence for multiple periods of loess deposition during the Late Pleistocene in the Missouri and Mississippi River Valley, United States: Implications for the activity of the Laurentide ice sheet

The loess stratigraphy of the mid-continental U.S. is an important proxy record for the activity of the Laurentide Ice Sheet in North America. One of the most outstanding problems is deciphering the age of loess deposits in this area during the late Pleistocene. Radiocarbon dating of snails and thermoluminescence dating of the fine-silt fraction (4–11 μm) from loess at the Loveland Loess type section, Loveland, Iowa and a recent excavation at the Pleasant Grove School section. Madison County, Illinois provide new chronologic control on loess deposition in the Mississippi/Missouri River Valley chronology indicates that the Loveland Loess is Illinoian in age (135±20 ka) but is not correlative with the Teneriffe Silt which is dated to 77 ± 8 ka. Concordant radiocarbon and thermoluminescence age estimates demonstrate that the Roxana Silt and a correlative loess in Iowa, the Pisgah Formation, is probably 40-30 ka old. These age estimates in conjunction with previous results indicate that there were four periods of loess deposition during the last 150 ka at 25-12 ka, 45-30 ka, 85-70 ka and at ca. 135 ± 20 ka. This chronology of loess deposition supports the presence of both a late Illinoian and early Wisconsinan loess and associated soils. Thus, there may be more than one soil in the loess stratigraphy of the mid-continental U.S. with morphologies similar to the Sangamon Soil. The last three periods of loess deposition may be correlative with periods of elevated dust concentrations recorded in the Dye 3 ice core from southern Greenland. This is particularly significant because both areas possibly had the same source for eolian particles. Reconstructions of atmospheric circulation for glacial periods show a southerly deflected jet stream that could have transported dust from the mid-continental USA to southern Greenland. Lastly, the inferred record of loess deposition is parallel to a chronology for deglaciation of the Laurentide Ice Sheet deciphered from chronologic and stratigraphic studies of raised glacial and marine sediments in the Hudson Bay Lowlands, Canada. These chronologies indicate that the Laurentide Ice Sheet was quite dynamic during the late Pleistocene, advancing and retreating across North America at least four times during the last 150 ka.

Fort Hays State University Natural Areas

Two natural areas are supervised by the Department of Biological Sciences at Fort Hays State University and are known as the and the Cedar Bluff In 1900 the Federal government granted old Fort Hays to Kansas. The 35 acre (14.2 ha) relict natural area was included in the 4160 acres (1683.5 ha) that became Fort Hays State University. The area is located in the SE 1/4 Sec. 1, T. 14S, R. 19W in Ellis County. The relict area has not been grazed since 1902. Ruts made by wagons coming to and from the Fort remain and can be seen cutting across the relict area. The topography of the relict area is characterized by steep to gentle slopes bordering a central drainage area. The site contains strata of the Niobrara Chalk, particularly the Fort Hays Limestone Member. A cap of Loveland Loess overlies the Fort Hays Limestone on upland areas. Parent materials consist of loess, limestone, alluvium, and shale. Four major communities are found in this area. The upland shortgrass community is dominated by buffalograss (Buchloe dactyloides), blue grama (Bouteloua gracilis) and western wheatgrass (Agropyron smithii), and occurs on deep loessial soils of the Mento series. The hillsides are dominated by big bluestem (Andropogon gerardii), little bluestem (Andropogon scoparius), and side-oats grama (Bouteloua curtipendula). The shallow calcareous Brownell soils underlying the hillside community support diverse forb populations. A homogeneous big bluestem community parallels the major drainage and is developed on alluvial and colluvial Armo soils. A large ravine traverses the relict area and is dominated by big bluestem, kochia (Kochia scoparia), and common sunflower (Helianthus annuus). The weediness of the lowland community is possibly the result of seepage from the farm pond located on the upper end of the drainage. The lowland has alluvial Roxbury soils.

The Sangamon Paleosol in Brown County, Kansas

A previously unstudied Sangamon paleosol was examined in Brown County, Kansas, to determine its characteristics and geographic distribution. The paleosol is buried by Wisconsinan loesses on uplands, where it is enriched in base elements eluviated from the loess. On shoulder slopes the soil is exhumed and leached. Stratigraphic evidence suggests that the soil is developed in thin Loveland loess over pre-Illinoian till beneath uplands while downslope, in exhumed locations, the Loveland member has been eroded and the truncated paleosol is formed only in till. The paleosol appears to have been a very strongly developed Ultisol or Mollisol at the time of burial. Evidence of the Sangamonian interglacial stage is well preserved in Kansas by the extensive and widespread occurrence of the Sangamon paleosol or geosol, as used by Morrison (1965). Although the type area for this paleosol is in Illinois (Follmer, 1978), its presence has been documented from Indiana (Hall, 1973; Ruhe et al., 1974; Ruhe and Olson, 1980) through Illinois (Follmer, 1979; Bushue et al., 1974), Nebraska (Schultz and Stout, 1945; Thorp et al., 1951), Iowa (Simonson, 1941; Ruhe, 1956, 1969), and Kansas (Frye and Leonard, 1952). In Kansas, the paleosol is best developed in the area adjacent to the Missouri River valley, as at the Loveland type section (Frye and Leonard, 1952) or the now destroyed exposure near Iowa Point (Frye and Leonard, 1949), both in Doniphan County. Research by Bayne et al. (1971), Caspall (1970), and Tien (1968) on the Sangamon soil in Doniphan County constitute additional studies of the paleosol in northeastern Kansas. Examinations of exposures of Quaternary deposits, coupled with numerous upland soil cores, have resulted in new data on the Sangamon soil in Brown County. Previous research on this paleosol had been mainly confined to adjacent Doniphan County. The purpose of this report is to document the presence of numerous exposures, many recent, of the Sangamon soil in This content downloaded from 207.46.13.124 on Wed, 22 Jun 2016 05:15:48 UTC All use subject to http://about.jstor.org/terms VOLUME 89, NUMBERS 3-4 153 Brown County, and to describe the characteristics and geographic extent of this paleosol. Data and results are summarized from Schaetzl (1983).

Thermoluminescence Dating of Loess from Western Iowa

AbstractThis study was conducted to evaluate thermoluminescence as an alternative to radiocarbon dating to determine age of soil materials low in organic carbon from major loess units from western Iowa. Thermoluminescence (TL) ages were determined for Upper Wisconsinan (Peoria), Basal Wisconsinan (“Farmdale”) and Loveland loesses using the fine‐grained technique on the 4 to 11 µm particle size fraction. Corrections were made for soil moisture and cosmic radiation influences. Thermoluminescence dating was effective in separating the three major loess units studied. The dates for Upper Wisconsinan (Peoria) loess were comparable to published radiocarbon dates, ranging between 13 150 to 24 130; however, there was considerable variability in the dates. The Basal Wisconsinan (“Farmdale”) loess gave considerably older ages (45 960–46 720) than reported with radiocarbon dating. Illinoian age Loveland loess yielded a date of 89 200 yr and was somewhat younger than presumed for the Illinoian advance. Thermoluminescence dating appears to be a viable alternative to radiocarbon dating of loess when organic material is not present, but more work is needed to rectify the age discrepancies. Although TL dating does not give dates in stratigraphic or chronological agreement with radiocarbon dating, it does differentiate the loesses studied.

Loess Composition in Southeastern Illinois and Southwestern Indiana

AbstractPeorian loess in southeastern Illinois and southwestern Indiana varied more in composition among the Wabash, Ohio, and Mississippi river source areas than did soils developed in the upper portion of the loess.Very low magnetic susceptibility was found in the gray, basal (Iowan or Morton) Peorian loess in the Wabash valley. Carbonate content was lower in Peorian loess of the Ohio valley than in that of the Wabash valley. Peorian loess was lower in clay and higher in silt content than Farmdale or Loveland loesses. Composition of the silt fraction, other than carbonates, did not vary greatly in Peorian loess of the three major source areas. Opal phytoliths and sponge spicules were present in all calcareous Peorian loess samples, and one unidentified microfossil was found in the Wabash valley loess. Illite was the dominant clay mineral in Peorian loess of the Ohio and Wabash valleys and expandable 2:1 minerals were dominant in Mississippi river loess. A high proportion of the expandable minerals in all samples was vermiculite. Chlorite and kaolinite were comparable in the Peorian loess of the three valleys.In comparison with the Peorian, the Farmdale loess had somewhat similar magnetic susceptibility, only secondary carbonates, and greater clay content. In the silt fraction, the Farmdale had lower Fe and Mn contents, less opal phytoliths, and similar sponge spicule content as the Peorian. The Farmdale was lower in illite, equal to or slightly higher in expandable clay minerals, and somewhat higher in chlorite and kaolinite contents than the Peorian.In comparison to the overlying Farmdale, the Loveland loess had strongly developed soils and less secondary carbonates. The silt fraction was lower in K2O and CaO contents, and lacked sponge spicules. The Farmdale and Loveland appeared to have similar clay mineral composition.The Ohio valley loess was most weathered and the five Wabash valley loess soils were least weathered as indicated by CaO/ZrO2 molar ratios of the A horizons. Alford and Sylvan soils, developed in Peorian loess of the Wabash, Ohio, and Mississippi valleys, appear to have no real differences in clay mineral composition in the B2 horizons, although illite may be higher than expandable clay minerals in the Ohio valley loess soils. A high proportion of the expandable clay minerals in all of the B2 horizons appeared to be vermiculite. The rather marked similarity of the clay of B2 horizons of the loess soils in contrast to the varied clay mineral composition of underlying loess, suggests that the surficial loess may have varied less than that deeper in the sections.

Loess Distribution in Southeastern Illinois and Southwestern Indiana

AbstractTotal loess (predominantly Peorian loess) thickness in southeastern Illinois and southwestern Indiana ranged from somewhat less than 40 inches to more than 300 inches, and the thinning rate of the loess was a linear function of the logarithm of the distance from the source. Peorian loess was present throughout the area, but Farmdale loess was present in significant amounts only in extreme southern Illinois and in extreme southwestern Indiana. Loveland loess was present sporadically beyond the limit of Illinoian glaciation. In the Wabash basin, loess thickens to the south as the valley becomes wider, the loess‐receiving landscapes become older, and the sediments in the valley become more silty. West‐northwest winds were important in the loess deposition of this region, but deposition of loess by easterly and southwesterly winds in the lower Wabash and Ohio river basins was shown to be more important than has been previously noted.

Mineralogical and Chemical Characteristics of Four Western Kansas Soils

Varied geologic materials, climatic conditions, topography, and native vegetation have produced a wide range in the physical and chemical properties of Kansas soils. Physically, the soils range from light-colored pervious sands to dark-colored slowly permeable clays. Chemically, they vary from the highly weathered, acid soils of the east to the neutral to alkaline and often calcareous soils in the west. Mineralogically, our knowledge is less complete. Only recently, with the development, acquisition, and use of x-ray and electron microscope equipment, and with the progress of the Kansas soil survey, has it been possible to analyze accurately the mineralogical composition of known soils. Swineford and Frye (14) in 1951 analyzed the mineralogical composition of Kansas surficial materials. They found that the silt-size fraction of the loessial deposits (parent material of soils) of western and northern Kansas contained quartz, feldspars, volcanic-ash shards, carbonates, and micas, with quartz making up more than half the volume. The clay fraction consisted of montmorillonite, illite, calcite, quartz, and feldspar, with a trace of kaolinite mineral. They attributed the presence of montomorillonite to the weathering of volcanic glass, commonly present in western Kansas loess whose source was the sediments of the Platt River, and northeast Kansas loess whose source was Missouri River sediments. Although they recognized a decrease in particle size with distance from the source this was not correlated with mineralogical composition. Hanna and Bidwell (6) confirmed their hypothesis regarding the source of the northeast Kansas loess, and in addition demonstrated a relationship between the soil profile particle size and distance from the Missouri River valley. Badgley (2) found the Peorian and Loveland loess of Decatur, Norton, Phillips, Smith, Jewell, and Republic Counties to contain an abundance of montmorillonitic type clay with the additional presence of interstratified clays in the more clayey buried paleosols, which he attributed to the deposition of potassium leached from the overlying loess.

Suggested New Type Section for the Loveland Loess in Western Iowa

The type locality of the Loveland formation was destroyed in 1957 when the site was used as a borrow pit for road construction. A new cut adjacent to the type section is described and characterized by textural, organic-carbon, and mineralogical analyses. The exposure is recommended as a new type section. The sequence and characteristics of the Pleistocene deposits exposed in the new section are similar to those of the former type locality except for the lack of reddish color in the Loveland loess and the presence of 13.5 feet of Farmdale loess, one of the largest thicknesses yet reported in Iowa. Distinguishing features of the Sangamon and Farmdale paleosols are color, texture, and content of organic carbon and the clay mineral vermiculite.