Illinoian Till Research Articles

AMELIORATION OF TYPIC AND ALBIC NATRAQUALFS USING CALCIUM CHLORIDE

Soils with natric horizons are prevalent in South Central Illinois where Peorian age loess overlies older surfaces underlain by Illinoian till paleosols. Such soils are classified as Natraqualfs and are intermixed with Albaqualfs that do not have natric horizons. The Natraqualfs make up from a few percent to more than 35% of the landscape, with Albaqualfs making up most of the landscape. Warm-season crops of corn and soybean on Natraqualfs are drought susceptible and have reduced yields because of shallow rooting and lesser amounts of plant available stored soil moisture compared with Albaqualfs; however, cool-season crops, such as wheat, have more uniform yields between Natraqualf and Albaqualf soil areas. Na+ was successfully moved to deeper soil depths within the soil when the natric horizon was treated with calcium chloride (CaCl2) and leached with water. Calcium chloride was used rather than calcium sulfate because CaCl2 solubility enhanced Ca++ concentration during the short-term leaching period. Treated and untreated plots were cropped from 2001 to 2004; however, there was no increase in corn or soybean yield during these four growing seasons for treated versus untreated plots, although the Na+ concentration was moved down in the profile from treatment with CaCl2 and leaching.

Geologic characteristics of the central stretch of the Ticona Channel, north-central Illinois

The Ticona Channel is located in north-central Illinois and occurs in Grundy, LaSalle, and Putnam counties. It is a buried bedrock valley that served as the principal paleodrainage system in north-central Illinois during the Illinoian and pre-Illinoian. This study focused on the part of the Ticona Channel within the Leonore 7.5 Quadrangle. The geometry and stratigraphy of sediments that fill the Ticona Channel were investigated using high-resolution, shallow seismic reflection profiling, traditional field geologic mapping techniques, borehole data, and water-well-log data. The valley is about 2 km (1 mi) wide and approximately 60 m (200 ft) deep. The U-shape channel is straight, trends east-west, and has only one mappable tributary. The valley is carved into the Pennsylvanian Carbondale Formation in the eastern part of the study area; it has incised into the Ordovician Prairie du Chien Group in the west. At its base, the Ticona Channel is filled with the Pearl Formation, which is coarse-grained sand and gravel that was deposited during the Illinoian glaciation. The Pearl Formation is overlain by Illinoian till of the Glasford Formation and is capped by Wedron Group sediments from the Wisconsinan stage.

Relationships Between Soil Characteristics, Distribution and Restoration Potential of The Federal Threatened Eastern Prairie Fringed Orchid, Platanthera leucophaea (Nutt.) Lindl

The Federal threatened eastern prairie fringed orchid (Platanthera leucophaea) occupies prairies, sedge meadows, bogs and fens, primarily north of the Wisconsinan glacial boundary. In the Midwest, where restoration is a recovery objective, its southern distribution is thought to be limited by the transition from nutrient-rich Wisconsinan-aged soils to more acidic nutrient poor soils of Illinoian-aged glacial drift. To better understand edaphic factors affecting its distribution and potential for establishment of new populations, we analyzed soil characteristics across the range of habitats occupied by this species, as well as from unoccupied habitats on the Illinoian Till Plain. We found that P. leucophaea occupies a complex edaphic gradient in variation of % organic matter, base content and soil texture. On Wisconsinan-aged substrates, it occurs in circum-neutral base-rich organic prairie soils in Illinois and Wisconsin and in less calcareous soils with slightly higher pH and lower organic matter content in Michigan lake plain prairies. Eastern sand prairie and sedge meadow habitats on Wisconsinan-aged drift and on unglaciated soils are moderately acid and nutrient poor, while bog and fen habitats are more strongly acidic and highly organic, with no evidence for an underlying calcareous substrate. In comparison, unoccupied prairie soils on the Illinoian till plain have lower pH, % organic matter and base concentrations. These soils also have relatively high % silt content which results in comparatively low available soil moisture holding capacity. This combination of soil conditions may exceed the tolerance limits of P. leucophaea and prevent this species from occurring south of the Wisconsin glacial boundary in the Midwest. On the other extreme, calcareous fens have high pH levels as well as extremely high calcium concentrations, which may exceed the tolerance limits of this species. These findings have implications for guiding efforts to establish P. leucophaea into habitats that should be suitable for this species.

A biogeochemical analysis of the Pocono till barrens and adjacent hardwood forest underlain by Wisconsinan and Illinoian till in northeastern Pennsylvania

We assessed soil and vegetation nutrient capital in the landscape mosaic of till barrens and hardwood forests on the Pocono Plateau in northeastern Pennsylvania. These shrublands, which contain an unusual abundance of rare species, occur primarily on Illinoian-aged glacial till, though some patches grow on Wisconsinan till. We hypothesized that barrens soil and vegetation contain smaller quantities of nutrients than forest soil and vegetation, and under the same vegetation, Illinoian till soils have a smaller nutrient content than Wisconsinan till soils. We measured pH, total C and N, and exchangeable Ca, Mg, K, and Al content of the soils and determined C, N, Ca, Mg, K, and P content of the vegetation. Litter and soil organic matter in the barrens have a higher C/N ratio than the forest. The Illinoian barrens Oa horizon is thicker and contains a greater quantity of exchangeable mineral nutrients than the other Oa horizons. Differences in vegetation nutrient capital strongly mirror differences in biomass. Our results show no strong association of parent material with soil or vegetation nutrient capital. Instead, they suggest that plant community characteristics, not soil nutrient availability, shape the landscape pattern of barrens and forest, particularly plant-driven positive feedbacks primarily involving fire frequency.

Loess stratigraphy of the Lower Mississippi Valley

Loesses of the Lower Mississippi Valley (LMV) are world-famous. Sir Charles Lyell (1847), Hilgard (1860), Stafford (1869), Call (1891) and Mabry (1898), thought the LMV loess was a single water deposit although “double submergence” was noted by Call (1891) and Salisbury (1891). Shimek (1902) and Emerson (1918) recognized LMV loess as a wind deposit which came from the valley. Although wind-deposited loess gained wide acceptance, Russell (1944a) published his controversial theory of “loessification” which entailed weathering of backswamp deposits, downslope movement and recharge by carbonates to form loess. Wascher et al. (1947) identified three LMV loesses, mapped distributions and strongly supported eolian deposition. Leighton and Willman (1950), identified four loesses and supported eolian deposition as did Krinitzsky and Turnbull (1967) and Snowden and Priddy (1968), but Krinitzky and Turnbull questioned the deepest loess. Daniels and Young (1968) and Touchet and Daniels (1970) studied the distribution of loesses in south-central Louisiana. West et al. (1980) and Rutledge et al. (1985) studied the source areas and wind directions which deposited the loesses on and adjoining Crowley's Ridge. B.J. Miller and co-workers (Miller et al., 1985, 1986, Miller and Alford, 1985) proposed that the Loveland Silt was Early Wisconsin rather than Illinoian age and advanced the name Sicily Island loess. They proposed the underlying loess was Illinoian and advanced the name Crowley's Ridge. We termed the loesses, from the surface downward, Peoria Loess, Roxana Silt, Loveland/Sicily Island loess, Crowley's Ridge Loess and Marianna loess. Researchers agree that the surfical Peoria Loess is Late Wisconsin and the Roxana Silt is Late to Middle Wisconsin, but little agreement exists on the age of the older loesses. Pye and Johnson (1988) proposed Early Wisconsin for the Loveland/Sicily Island. McKay and Follmer (1985) suggested this loess correlated with a loess under Illinoian till. Clark et al. (1989) agreed on Crowley's Ridge, but suggested the Loveland/Sicily Island loess on Sicily Island was older. Mirecki and Miller (1994) and Millard and Maat (1994) suggested an Illinoian age for the Loveland/Sicily Island loess. Miller and co-workers suggested, as did Pye and Johnson (1988), an Illinoian age for the Crowley's Ridge loess. McKay and Follmer (1985) suggested it correlated with a loess under “Kansan” till. Stratigraphy indicates the Marianna is the older of the five loesses. Researchers identified loess on both the east and west side of the LMV as well as on higher terraces within the valley. Many researchers assumed unaltered loesses were commonly yellowish brown, and silts or silt loams (West et al., 1980; Miller et al., 1986). The nonclay fraction of unweathered LMV loesses was dominated by quartz followed * Corresponding author. by carbonates, mainly dolomites, followed by feldspars, and micas. Clays were dominated by montmorillonite followed by micaceous minerals, kaolinite and vermiculite (Miller et al., 1986). Soils in the Crowley's Ridge loess are most developed, followed by the soils in the Loveland/Sicily Island which are more developed than the modern soils in the Peoria Loess. Soils in the Roxana and Marianna loesses are least developed and the Farmdale Soil of the Roxana is the weaker of the two (Miller et al., 1986). There is certainly overlapping range in the degree of soil development in the various loesses.

Multiple pre-Wisconsinan glaciations along the northwestern edge of the Allegheny Plateau in Ohio and Pennsylvania

Stratigraphic studies of the glacial geology of the northwestern margin of the Allegheny Plateau of northeastern Ohio and northwestern Pennsylvania include evidence for multiple pre-Wisconsinan glaciations. Near the former eastern margin of the Scioto lobe at Mount Gilead, Ohio, Millbrook, Gahanna, and Chesterville tills have an inferred Illinoian age based on thermoluminescence ages of 146 000 ± 25 000 and 124 000 ± 16 000 BP from an overlying silt interpreted as loess. Northampton Till overlies Millbrook Till of the Killbuck lobe and its correlative Mogadore Till of the Cuyahoga lobe, but does not overlie the correlative Titusville Till of the Grand River lobe. There are signficant differences in carbonate contents among these tills. Millbrook Till and its equivalents contain more kaolinite than other tills, and the Northampton Till contains more clay. Millbrook Till and its correlatives represent the most extensive Illinoian glaciation of the plateau, whereas the other Illinoian tills were deposited by ice that flowed a shorter distance onto the Allegheny Plateau. Butler, Mapledale, and Slippery Rock tills, formerly assigned to an Illinoian glaciation, are pre-Illinoian in age. Scarcity of materials for the dating and the lack of recognizable paleosols separating the tills from Wisconsinan deposits inhibits the reliability of the chronological classification of these tills.

Vegetation ecology of flatwoods on the Illinoian till plain

Abstract. Midwestern flatwoods are open woodlands of level uplands and terraces that occur on impervious subsoil horizons and have seasonally wet and dry soils. Vegetation and soil data from six flatwoods remnants on the Illinoian till plain in Illinois were examined to identify what biotic and edaphic factors control vegetation structure, composition and diversity. Soils at all sites are characterized by the presence of argillic horizons (clay pans). Two soil ordination groups were clearly defined, each characterized by separate parent material origin. Canopy and subcanopy composition are dissimilar at sites with soils developed entirely in loess; more similar at sites on lacustrine soils (including aeolian sand). Quercus stellata was by far the most important tree species followed by Q. marilandica. Q. stellata importance was negatively correlated with Ca, particularly in the A‐horizon. Q. marilandica shows a positive correlation to sand and magnesium, particularly in the B‐horizon, and was most frequent and abundant on soils where Ca/Mg ratios are lower than 1.0 in the E and B‐horizons. Total stem density of woody plants was positively related to total available soil moisture as influenced by depth to clay pan and soil textural differences. Ground‐cover species richness and diversity were inversely related to tree and total woody stem density and tree diversity. One site with a recent history of annual prescribed fire had significantly greater ground‐cover species diversity compared with the unburned sites. Evidence from stand structure and similarity between canopy and subcanopy strata, if reflecting stationary processes of canopy recruitment, suggest that disturbances historically maintained the importance of oak species in most flatwoods. Prescribed fire appears to maintain or enhance ground‐cover species diversity at one flatwoods remnant, suggesting that fire could be used to maintain compositional stability at sites with greater available soil moisture.

Sodium‐Affected Soil Identification in South‐Central Illinois by Electromagnetic Induction

AbstractThe irregular shape, small size, and spotty occurrence of sodium‐affected soils (NaAS) in moderately thick to thin loess over Illinoian till have continued to slow mapping in south‐central Illinois. Use of a Geonics EM‐38 ground conductivity meter to recognize soils with natric horizons in Tennessee suggested that this device would be useful in Illinois. We selected eight areas of NaAS in five counties of south‐central Illinois to find if the EM‐38 would be useful for predicting exchangeable sodium percentage (ESP). Approximately 225 observation points, spaced at 10‐m intervals, were established in each area and 107 sample cores were collected for laboratory analyses. Weighted averages of the ESP, electrical conductivity of the saturation extract from a saturated soil paste (ECe), and field pH data for 0 to 75‐ and 75 to 150‐cm depths were compared with the horizontal (EMh) and vertical (EMv) responses and the mean ESP data increases with depth, i.e., 7.0 at 35 cm, 9.7 at 75 cm, and 12.5 at 135 cm. The EMh readings correlate almost as well with ESP (r = 0.73) as with ECe (r = 0.76) for the 0‐ to 75‐cm depths. The EMv readings correlate slightly better with ESP (r = 0.76) than with ECe (r = 0.68) for the 75‐ to 150‐cm depth. These results show that EM readings may by used to predict ESP. The correlations of the depth‐weighted average ESP at the maximum depth for meeting natric horizon criteria in these soils (75 cm), and the EMv readings show that the EM‐38 provides a rapid and accurate method to describe the composition of the map units of NaAS on moderately thick to thin loess over Illinoian till in south‐central Illinois.

Comparisons of Humic Substances Extracted from Contiguous Alfisols and Mollisols of Southwestern Ohio

AbstractHumic and fulvic acids extracted from contiguous Alfisols and Mollisols were characterized to determine if any dissimilarities could be documented between humic substances extracted from soils formed under nearly identical environmental conditions, but belonging to different taxonomic classes. Comparisons of humic substances from two Alfisol‐Mollisol pairs, one from the Wisconsinan and one from the Illinoian till plain of southwestern Ohio, were based on wet chemical, infrared, and 13C cross‐polarization magic angle spinning nuclear magnetic resonance (CPMAS NMR) spectroscopy studies. Using 0.1 M NaOH, more humic substances were extracted from the Mollisols than the Alfisols, with the majority being humic acids. Small amounts of fulvic acids were recovered from all pedons. Data from infrared and 13C CPMAS NMR spectroscopy indicate that humic acids from both the Alfisols and Mollisols are dominated by alkyl‐substituted aromatic structures, followed by aliphatic, O‐substituted alkyl, carboxylic acid, and small amounts of carbonyl structures. Whereas 13C NMR spectroscopy data suggest Mollisol humic acids contain higher aromatic and carboxylic acid contents than those of the Alfisols, Alfisol humic acid spectra show more evidence for phenolic‐OH groups and lignin and lignin‐like products than those of the Mollisols. Fulvic acids from Alfisols and Mollisols contained mostly aliphatic, O‐substituted alkyl, and carboxylic acid, followed by aromatic groups and small amounts of carbonyl groups. The proportion of nonaromatic and aromatic structures in the fulvic acids of the Alfisols and Mollisols was similar, but slight differences were noted in elemental ratios and 13C NMR spectra. Although only minimal differences were noted among fulvic acids, differences were evident in the chemical and structural properties of humic acids from contiguous Alfisols and Mollisols in southwestern Ohio.

Clast ploughing, lodgement and glacier sliding over a soft glacier bed

Rarely‐preserved features indicative of clast lodgement are exceptionally well preserved near Peoria, Illinois, on the contact surface between Illinoian till and underlying glacifluvial sand due to synsedimentary cementation of the substrate contact. Features preserved on the cemented contact surface record a history of particle transport, lodgement by ploughing into a deformable substrate, and subsequent overriding by abrasive debris‐rich ice. Linear grooves and frontal sediment prows suggest that clasts embedded in the glacier sole ploughed through the soft, deformable bed. Increasing form resistance by the enlargement of sediment prows that developed on the lee side of clasts and deeper penetration of the clasts into the substrate eventually exceeded the force exerted on the clasts by ice flow, and the clasts lodged. Subsequently, clasts were abraded on their up‐ice flanks and plucked on their down‐ice flanks, resulting in stoss‐lee morphology. These features offer direct information on the nature of the interface between aglacier and a soft, deformable substrate such as characterized large areas of former ice sheets.

Transitional Vermiculite‐Smectite Phases in Aqualfs of Southwestern Ohio

AbstractThe clay mineralogy of two Aqualfs occurring on the Illinoian till plain of southwestern Ohio was investigated in order to (i) determine the clay mineral distribution with depth, (ii) examine the clay mineral weathering sequence, and (iii) identify the 2:1 mineral species in which hydroxy interlayers had formed. Despite the presence of multiple parent materials, no obvious discontinuities in clay mineralogy were observed. A weathering sequence involving the transformation of clay mica to vermiculite to low charge vermiculite/high charge smectite occurred. Alkylammonium ion exchange data indicated that weathering created a heterogeneous charge distribution in the 1.4‐nm (expandable) mineral phase resulting in mixed low‐and high‐charge interlayers. The low‐charge interlayers readily formed bilayer complexes with ethylene glycol (1.7 nm), and also accommodated double layers of glycerol (1.8 nm) when the mean layer charge was <0.65. Reductions in layer charge were correlated with the oxidation of octahedral Fe(II) and the expulsion of K and Mg from the mineral structure. The expansion of 2:1 layer silicates in horizons near the soil surface was restricted as a result of Alhydroxy interlayering. After interlayer materials were removed with boiling 0.33 M Na citrate, the previously interlayered minerals exhibited x‐ray diffraction effects following Mg saturation and ethylene glycol and glycerol solvation that were indicative of vermiculite.

Micromorphology of seasonally wet soils on the Illinoian Till Plain, U.S.A.

Two seasonally wet soils from southwestern Ohio in the north-central region of the U.S.A. were studied in order to relate micromorphology to pedogenic processes associated with fluctuating oxidation-reduction conditions. The soils formed in approximately 70 cm of Late Winconsinian loess overlying a composite paleosol developed in Early Wisconsinian loess and Illinoian till. Alternating oxidation-reduction conditions in the upper 150 cm were accompanied by abundant albic neoskeletans, Fe-Mn nodules, and partially decomposed, grainy argillans. Conditions were most reduced along saturated macropores between ped faces in about the upper 80 cm where thick albic neoskeletans occurred. Horizons from 50–80 cm were extensively degraded and were characterized by many Fe-Mn nodules and gray, eluvial zones (albic neoskeletans) surrounding islands of brown sesquioxidic material having inundulic plasmic fabrics. Argillic horizon degradation is one of the most important genetic processes in these soils. Embedded grain ferriargillans enriched in goethite were abundant in the lower paleosols from approximately 150–250 cm. Neogoethans and neomangans were evident at a depth of approximately 2 m which is the lowest point to which the water table falls in these soils each year.

Stratigraphy and Genesis of Polygenetic Soils on the Illinoian Till Plain of Southwestern Ohio

AbstractThree pedons each of Clermont (Typic Glossaqualfs) and Avonburg (Aeric Fragiaqualfs) soils were investigated on the Illinoian till plain of southwestern Ohio in order to evaluate parent material stratigraphy and to determine if paleosols were substantially altered following burial by a thin mantle of loess. The relationship between fragipan development and paleosol properties was also examined. The soils were found to have formed in 57 to 69 cm of Late Wisconsinan (Peoria) loess overlying a composite Early Wisconsinan and Sangamon paleosol. The Sangamon paleosol, which was most strongly developed at approximately 150 to 200 cm, was formed in Illinoian till. The material from about 70 to 140 cm consisted of a mixture of Early Wisconsinan loess and Illinoian till with till characteristics dominating. Evidence for a mixed zone in the upper paleosol included (i) a higher silt content than the lower paleosol, (ii) a maximum in elemental Ca in the total silt fraction, and (iii) an abundance of pedotubules in up to 50% of some horizons suggesting that mixing was caused by bioturbation. Modification of the paleosols has occurred as evidenced by recharge with secondary carbonates and bases leached from the overlying loess. A fragipan was identified in only one Avonburg pedon that had a clay content of 27% in the upper part of the paleosol as compared to 31 to 38% for the other pedons. Fragipans appear to have formed in these soils only if the clay content of the upper part of the paleosol is currently less than about 30%.

Soil Structure and Associated Rooting Behavior in Minesoils

AbstractThe objective of this study was to identify and describe soil structural patterns and rooting behavior in reclaimed minesoils. The soil chosen for this study consists of approximately 0.4 m of topsoil (A horizon) material placed on approximately 1.5 m of a blend of B horizon, mixed paleoloesses, Sangamon paleosol, and Illinoian till. Four soil pits were excavated, exposing root systems of the corn test crop. Detailed soil and root pattern descriptions were made in each pit. Root patterns were depicted using the profile wall method. An outline of soil structural pattern was superimposed over the root pattern to provide a pictorial relationship between the two. Differences in the physical condition of subsoils were distinguished on the basis of the soil descriptions and statistical analysis of the root length determinations. An artificial soil structure was characterized and attributed to particular mining and reclamation practices. The structural arrangement consists of rounded aggregates loosely compressed together, that fall within the size classes currently used for blocklike and polyhedral aggregates. Plant rooting was distinctly more profuse where this structure was present than where the soil material was massive and compact. It is proposed that structural differences among newly constructed soils are of such significance that they should be carefully characterized and described, and where appropriate used for series level separations. Operations using a mining wheel in combination with belt transportation favor the formation of the more desirable fritted structure, whereas operations using scrapers exclusively favor the formation of the less desirable massive physical condition.

Soil Properties and Chemical Composition of Tree Leaves in Southern Indiana

AbstractSoils developed from gray‐green shale in southeastern Indiana and neighboring states have low forest site quality and low productivity for farm crops. In this study the Rarden soil, formed from gray‐green shale, was compared with the Trappist soil (moderately productive), developed from black carbonrich shale, and the Hickory soil (highly productive), developed from Illinoian till. The soils were on westerly‐facing shoulder and backslope landscape positions. Crystals occurring as small patches in the B3 of Rarden were identified as barite (BaSO4) in prismatic, hexagonal‐tabular, or octagonal‐tabular shapes. A pedon of the Rarden soil contained about two‐thirds as much extractable Ba as Ca. Leaves from three hardwood species were analyzed for 15 elements at each site. Flowering dogwood (Cornus florida L.) leaves accumulated Ca and, especially, Al to a much greater extent than sugar maple (Acer Saccharum Marsh) or white oak (Quercus alba L.), whereas sugar maple tended to accumulate Mn. Leaf samples collected in July and September showed no significant differences in concentration of the major nutrient elements P, K, and Ca, but did show differences in concentration of several of the minor nutrients. No evidence was found that Ba or other minor elements caused toxicities or deficiencies. The contents of extractable Ca and Al in the soil were reflected in their concentrations in flowering dogwood leaves.

Chemical and Mineralogical Properties of the Fragipans of the Cincinnati Catena

AbstractThis is a study of fragipan soils on two transects on the Illinoian till plain of southern Indiana. These soils were thought to be formed in 50 – 100 cm of loess over Illinoian Age till. In the soils sampled for this study, the surface of Sangamon Age paleosol in Illinoian till was located at a 2‐m depth. Two other parent materials above the paleosol were described. The surface parent material may be loess, but the parent material above the paleosol is too sandy to be completely loess.In sodium citrate‐bicarbonate‐dithionite extracts, SiO2 contents reached a maximum in the fragipan horizons. The Al2O3 contents were highest in the argillic horizon. Extraction of natural clods from the fragipan matrix by various solutions under vacuum showed that extractants that removed Fe and Al did not affect the cohesion of the fragipan matrix. Silica was extracted by sodium hydroxide which also broke down the fragipan matrix. Carbonate and bicarbonate solutions also broke down the fragipan matrix and may have caused a reaction between soluble Si and the soil material. Thus we consider Si to be the binding agent, along with clay, that produces the characteristic brittleness of the fragipan horizon.

Significant Multiple Pre-Illinoian Till Exposure in Southeastern Indiana

Five tills are exposed in a stream cut south of the Wisconsinan glacial boundary in Decatur County, southeastern Indiana. All tills are mineralogically or texturally distinct. The uppermost till is leached 7 ft and is regarded as Illinoian. Because there is a thick paleosol (7 ft of leaching and 11 ft of oxidation) in the surface of the till immediately below the Illinoian till, four of the tills in this section are considered pre-Illinoian in age. This is the largest number of pre-Illinoian tills known east of the state of Illinois. On the basis of lithologic characteristics and fabric, all tills appear to have been deposited by ice moving from a northerly or westerly direction. The chert-rich basal till of this section is very distinctive and, where described from other localities in southeastern Indiana, always is the lowermost till of the section. For this reason, and because the till contains a high percentage of weathered chert pebbles and non-calcareous “red” clay material, it is regarded as representing the first ice advance into southeastern Indiana. Although no definite age can be assigned to the pre-Illinoian tills, it seems that because of their textural and mineralogical differences they represent (1) deposition by nearly contemporary ice sheets advancing from slightly different directions and/or (2) deposition by non-contemporaneous ice sheets which advanced from a common direction after erosion had modified the pre-existing surface enough to expose new source materials.

Illinoian-Wisconsinan Pleistocene Deposits at Eaton, Ohio

Detailed examination of Pleistocene deposits along Seven Mile Creek in Eaton, Ohio, reveals that the exposure contains an Illinoian till and a previously undescribed Sangamon paleosol. The sequence described indicates that the area had been covered by three glacial advances during Wisconsin time rather than two advances, as previously supposed. The paleosol and the basal Wisconsinan drift are correlative with the glacial sequence of southeastern Indiana.

Weathering of glacial tills in Indiana; [Part] 2, Heavy minerals

ABSTRACT Petrographic data from weathered profiles developed on Wisconsin, Illinoian, and Kansan tills in Indiana reveal that these profiles differ from each other in the relative stability of their heavy mineral assemblages. The weathering profiles developed on Wisconsin till are distinctly different from those on the Kansan and Illinoian with respect to heavy mineral alteration, but the differences are not very pronounced between the weathering profiles developed on the Illinoian and Kansan tills. The heavy minerals are more altered in the older tills and the amount of altered products increases with greater duration of weathering.

Source and Distribution of Sodium in Solonetzic Soils in Illinois

Possible sources of extractable Na (water-soluble plus exchangeable) considered for Illinois solonetzic soils were: Pennsylvanian bedrock, Illinoian till, Farmdale and Peorian loess, and ocean spray salts from rain. Extractable Na in Illinois sononetzic soils originated chiefly from the weathering in situ of Na-rich feldspars of the parent loess. Members of the albite series (namely, albite and oligoclase) and the Na-rich microcline, anorthoclase, aggregate 70 to 80% of the silt-sized Na-bearing minerals which comprise 75 to 90% of the total mineral Na in these soils. Sufficient Na has weathered from the 50 to 5µ silt fraction in solonetzic soils to account for accumulations of extractable Na currently present in their B horizons. Little evidence of local variability in loess or differential weathering between solonetzic and associated soils suggests that differential redistribution of soluble products of weathering is responsible for extractable Na accumulations in Illinois solonetzic soils. It is believed that the local distribution of solonetzic soils is correlated with more permeable till zones of the highly impervious, underlying Illinoian till paleosol. Based on this assumption, a redistribution mechanism involving aqueous movement and differential segregation of soluble products of weathering is presented.