Peoria Loess Research Articles

Clay-mineral indicators of glacial and nonglacial sources of Wisconsinan loesses in Southern Indiana, U.S.A.

Clay-mineral compositions of Peoria loess of later Wisconsinan age derived from Wabash Basin and Ohio Basin riverine sources differ in southern Indiana. In the Wabash province the composition is illite > expandable clay minerals > kaolinite and relates to the clay-mineral composition of glacial drift in the basin of 91% glacial cover. In the Ohio province the composition is expandable clay minerals > or ⋍ illite > kaolinite and relates indirectly to the clay-mineral composition of the Sangamon Soil terrain on bedrock. Above the confluent Wabash Basin, 77% of the Ohio Basin is unglaciated. The clay-mineral composition of thin Farmdale loess of earlier Wisconsinan age also relates to the composition of the paleosol terrain. During Peorian time while glacial outwash was supplying loess source materials to the valleys in the Wabash Basin, ordinary alluvium derived from soils and bedrock in unglaciated terrain was supplying loess source materials to the valleys in the Ohio Basin.

Sources and Properties of Loess Deposits on Crowley's Ridge in Arkansas

AbstractCrowley's Ridge is a north‐south trending erosional remnant of Coastal Plains sediments capped by multiple loess deposits. Due to activities of ancestors of the Mississippi and Ohio rivers, the extensive flood plains, both immediately east and west of this ridge, were plausible loess source areas. This long, narrow ridge was transected normal to its long axis to separate and investigate the multiple loess deposits and to determine the source area of each loess. Morphology, total Ca and K distribution, and clay distribution were used to differentiate the loess deposits. Particle size, expressed on the clay‐free basis, was used to determine the source area of each loess.Three loess deposits were identified on Crowley's Ridge. The surface loess is 2.8 to 7.4 m thick and contains the surface soil which has undergone sufficient development to form a fragipan. This loess was correlated as Peoria Loess and was deposited from the flood plain east of Crowley's Ridge. The middle loess shows evidence of weak soil development. This thinner, 1.3 to 1.8 m thick, loess was correlated as Roxana Silt and evidently also had its source in the flood plain east of Crowley's Ridge. The basal loess contains a strongly developed paleosol at its surface and ranges from 2.3 to 8.6 m thick. This deposit was correlated as Loveland Silt and apparently had been deposited from the flood plains on both the east and west sides of Crowley's Ridge.

Fragipan Horizons in Soils of the Memphis‐Loring‐Grenada Sequence in West Tennessee

AbstractThe distribution of soils on the loess‐mantled landscapes of west Tennessee does not fit the traditional concept that the older, more strongly developed soils occur on the more stable positions in the landscape. The objective of this study was to attempt to ascertain whether the development and distribution of these soils were related to weathering associated with the modern landscape or whether they were in part relict from the earlier period of weathering. Power augers were used along west to east transects to determine the characteristics and thickness of the three identifiable loess sheets involved and to explore their relationship to the distribution of soils within landscapes at different points along the loess thickness sequence. The top of the Roxana loess was everywhere marked by a distinctly brittle zone 1 to 2 m thick. Evidence that the brittle zone in the top of the Roxana is a product of pre‐Peorian weathering is the fact that it occurs under calcareous loess near the bluff and can be traced eastward under the thinning Peoria loess until it grades into the fragipan horizons within the sola of the Loring and Grenada soils. The stratigraphic, geomorphic, and morphologic evidence leads to the conclusion that the fragipan horizon of the Loring and Grenada soils is a relic of pre‐Peorian weathering that has undergone subsequent modification by processes related to the modern surface.

Loess in Ohio in Relation to Several Possible Source Areas: I. Physical and Chemical Properties

AbstractThin loess deposits east of the Little Miami, Scioto, and Muskingum rivers in Ohio were investigated (i) to test the hypothesis that these river valleys were source areas for the loess that adjoins them, (ii) to determine if multiple loess strata occurred within any of the loess deposits, and (iii) to approximate, where possible, the geologic age of the loess. The loessial materials were investigated using morphological, chemical, and physical parameters. Particle‐size data were expressed on a fine earth and clay‐free basis. The fine earth basis was useful in detecting pedogenic development. Clay‐free data were used in establishing changes in parent material with depth and, perhaps more importantly, in development of relations between particle‐size and distance from proposed source areas.Scioto and Muskingum river valleys were the chief source areas for the loess in the adjoining study areas, but the Little Miami Valley was not the primary source of the loess in the study area adjacent to it. Multiple loess deposits were identified only adjacent to the Muskingum River. All upper loess units were considered to be of comparable age; Late Wisconsin (Peoria Loess). The middle loess adjacent to the Muskingum River was considered to be Farmdale (Roxanna Silt) and the lower loess at the same site was considered to be Loveland loess (Loveland Silt) and contained a well‐developed Sangamon paleosol.

Slick Spots in Southeastern Nebraska—Patterns and Genesis

AbstractSlick spots formed in Peoria loess near the crests of interfluves in southeastern Nebraska were studied in relation to their distribution and genesis. Peoria loess forms a discontinuous mantel over a maturely dissected plain of Kansan till. Soils within the slick spots are low in chroma, contain some soluble salts, and have more extractable sodium than associated soils formed in Peoria loess. Calculations indicate that clay formed per unit of nonclay lost was greater in a slick spot soil profile than in an adjacent soil profile. Subsurface data indicate that the configuration of an erosion surface cut into Kansan till underlying the slick spot and the differential permeability of Illinoian sediments above the till contribute to the occurrence of a perched ephemeral water table in the loess beneath the slick spot. The evidence suggests that soluble products of weathering, including Na and Ca, are added to the slick spot by capillary rise from a perched water table following periods of above average precipitation and accumulate in the slick spot during subsequent periods of intense evapotranspiration.

Loess Distribution as Revealed by Mineral Variations

AbstractThe apparent physical uniformity of various loess deposits has often led in the past to conclusions of uniform composition and constant rate of deposition for loess formations. These assumptions have been used in many evaluations of soil development and in explaining the distribution of various soils. The existence of identifiable increments of characteristic composition within Peoria Loess not only indicates compositional variations but permits evaluation of the regional distribution of individual loess increments. Unique mineralogy (particularly clay‐mineralogy) of the loess increments is attributed to major changes in the origin of valley loess source sediments.The consistent identification and pattern of four distinct zones within Peoria Loess in Illinois east of the Illinois River Valley reveal that the rate of loess deposition has not been constant. Rather, the upper younger loess increments are most dominant and more widely distributed and therefore most important as soil forming material. This implies that the soils of the maturity or development sequence in Illinois have all formed in the same relatively young increment of Peoria Loess. The characteristies of these soils which vary from weakly‐ to moderately‐developed Udolls to very strongly‐developed Albaqualfs cannot be attributed to their age differences.

The Relationship Between Rainfall Frequency and Amount to the Formation and Profile Distribution of Clay Particles

AbstractFor Typic Argiudolls in Illinois the amount of pedogenic clay particles formed, over that inherited from the calcareous Peoria loess, seems to be controlled by rainfall frequency. The amount of solution leaching through the soil, as inferred from the amount of rainfall, was not related to the amount of pedogenic clay particles formed. This finding may help explain why the clay minerals found in the argillic horizon of some soils are not in the clay mineral stability field predicted by dilute solution chemistry.The distribution of clay within the soil profile is related to the amount and distribution of rainfall (leachable water), depth of leaching, and natural drainage class.

Stratigraphy and origin of the paha topography of northwestern Illinois

The paha of northwestern Illinois are longitudinal dunes developed in toto during Woodfordian time. Cores of noneolian materials, such as are typical in the paha of northeastern Iowa, are either not present or much reduced in numbers in the paha of Illinois. Variation in the thickness of the surface blanket of Peoria Loess accounts for the total topographic expression of the Illinois paha. Underlying the Peoria Loess is a sequence of Pleistocene deposits consisting of two tills of Illinoian age, and the Plano Silt and Roxana Loess of Altonian age. Radiocarbon ages obtained from the Plano Silt range from 41,900 ± 1300 to 34,630 ± 710 radiocarbon years B.P.

Pedogenic Distribution of Zinc in Mollisols and Associated Entisols in Nebraska

AbstractThe distribution of total Zn in a Udie Haplustoll (Moody) and a Typic Argiustoll (Holdrege) formed in Peoria loess in Nebraska is related to the accumulation of illuvial clay in these soils. In Typic Ustorthents (Crofton and Coly) formed in Peoria loess, a comparable distribution of noncarbonate clay and total Zn does not occur. Larger amounts of Zn in noncarbonate clay from the upper sola of the four profiles than in noncarbonate clay from their C horizons suggest that Zn is released from soil minerals and cycled by vegetation during biopedogenic weathering, then becomes associated with noncarbonate clay in the A horizons following decomposition of plant residues. In Moody and Holdrege, however, maximum amounts of Zn in the total soil occur in the B horizons of clay maxima, suggesting that Zn moves in association with clay from the A to the B horizons during the genesis of these soils.

Loess Distribution from a Source

AbstractLoess thickness and particle size changes along six Peoria loess traverses in Illinois and southwestern Indiana were investigated by fitting the data to various mathematical models by computer. An exponential model, a logarithmic model, a power function, and an additive exponential model developed in this study were tested. The decrease in mean particle size, which is due to changes in the coarse silt content, both windward and leeward from the source is explained best by the additive exponential model. Mean particle size changes much more rapidly near the source than afar.Leeward of the source, two changes in the rate of loess thinning occurred. The change closest to the bluff is related to particle size differences with distance from the source. The second change is attributed to greater loess deposition in a wider zone near the source by winds from different directions. Windward of the source, no change in the rate of loess thinning due to particle size differences was observed.Based upon the particle size and thickness data presented, the decrease in loess thickness from its source is explained best by an additive exponential model. Leeward of the source where two changes in the rate of loess thinning occur, three exponential terms are needed to accurately characterize loess thickness. The decrease in loess thickness with distance from the source which is due to the more rapid decrease in particle size near the source is defined by the first exponential term. The decrease in loess thickness associated with deposition by winds of different directions is described by the second exponential term. The third exponential term depicts the regional loess thinning due to a decrease in the number of loess particles with distance from the source. Windward of the source only two exponential terms are needed to accurately describe loess thickness because no change in the rate of loess thinning due to particle size differences was observed.

Stratigraphy of the Late Pleistocene Loesses of Kansas

The post-Yarmouthian Pleistocene of Kansas is characterized by extensive loess sheets which contain buried soils. The loesses and associated fluvial deposits are classed in Kansas as Crete, Loveland, Peoria, and Bignell members of the Sanborn formation. Based on lithologic characteristics, sequence, content of fossil mollusks, and stratigraphic continuity of buried soils, the members are identified throughout their extent in Kansas. Also trustworthy correlations with late Pleistocene deposits in Nebraska and Iowa, including the type Bignell and Loveland loesses, can be made. The Peoria loess of Kansas is shown by faunal evidence to be equivalent to the Peoria (Iowa and Tazewell) loess of central Illinois.

Petrography of the Peoria Loess in Kansas

The surficial material throughout one-third of Kansas is the Peoria silt (loess) member of the Pleistocene Sanborn formation. Samples of this loess from an area 400 miles east-west by more than 200 miles north-south, which have been analyzed for particle size, chemical composition, and mineral constituents, show that major constituents of the silt-size fraction are quartz, feldspars, volcanic-ash shards, carbonates, and micas; quartz constitutes more than half the volume. A large suite of secondary minerals is present. The clay fraction consists of montmorillonite, illite, calcite, quartz, and feldspar, with a trace of a kaolinite mineral. Evidence used to determine source areas includes (1) progressive linear change in texture; (2) geographic variations in thickness; and (3) minor geographic differences in composition. The Platte River Valley is identified as the primary source for the Kansas region, and the Arikaree, Arkansas, and Republican valleys as important supplementary sources. The Missouri is the predominant source in the northeastern corner of Kansas. Other principal valleys, which lacked glacial outwash, were not source areas of Peoria loess in Kansas.

Stratigraphic Zonation of the Peoria Loess in Kansas

An extensive thick sheet of generally calcareous, fossiliferous occurs at or near the surface in northern, central, and southwestern Kansas. This loess, the Peoria silt member of the Sanborn formation in Kansas classification, lies above the Sangamon (Loveland) buried soil and includes at the top the Brady buried soil, hitherto of uncertain age. The history of the term Peorian loess is reviewed, and the age of the Peoria is considered in the light of published reports. Three zones are recognized in the Peoria in Kansas: (1) a basal zone, devoid of molluscan fossils; (2) a lower molluscan faunal zone; and (3) an upper molluscan faunal zone. On stratigraphic and faunal evidence the basal zone is correlated with the Farmdale of Illinois, the lower zone with Iowa loess, and the upper zone with Tazewell loess. The Brady soil is shown to have been formed in post-Tazewellian-pre-Caryan (or pre-Mankatoan) time, designated the Bradyan interglacial interval.