Uniform Parent Material Research Articles

The distribution of minor elements among the components of a soil developed in loess

This previously described buried soil, developed in uniform parent material, was used to study the relative movements of elements and other soil components down the profile. Samples from all horizons were treated with hydrogen peroxide and ammonium oxalate, under ultra-violet light, to remove organic matter and sesquioxides, and the residues were subdivided into six particle size fractions. Downward movement of clay (< 0.5 μm) was accompanied by movement of extractable Al 2O 3 and Fe 2O 3, thus identifying these as part of the mobile fraction. The less close relationship of extractable Fe 2O 3 to the clay suggested that it also occurred partly in coarser aggregates. Proportions of minor elements extracted varied from < 1% for Sr to nearly complete extraction of Co, Cu and Mo in some horizons. The extractable fractions of most minor elements throughout the profile behaved more like Fe 2O 3 than Al 2O 3. In the extraction residues, nearly all elements were enriched in the clay fractions relative to the coarser fractions; this being greatest for V and Fe.

Parent Material Uniformity and Origin of Silty Soils in Northwest Arkansas Based on Zirconium‐Titanium Contents

AbstractUniformity of parent material studies were made of 15 soils overlying various geologic materials, utilizing petrographic and X‐ray spectographic techniques. Zr and Ti contents were used as tests for a “loess” versus a “residual silt” hypothesis for the origin of silty soils in northwestern Arkansas. The lack of significant deviations with depth in Zr and Ti contents and ratios points to an absence of lithologic discontinuities in soils suspected of having an upper loess parent material. It is concluded that these soils are formed in local materials and not from extra‐regional loess. It is proposed that prolonged weathering of local rocks together with reworking by mass movements, water, and wind on a local basis has resulted in a rather homogeneous regolith on the older gently sloping landscapes over cherty limestones and siltstones. The local nature of the soil parent materials is also indicated by the fact that Zr and Ti contents in the very fine sands were found to be related to underlying rocks being highest (ZrO2, 0.30%; TiO2, 0.26%) in soils over sandstone and lowest (ZrO2, 0.03% TiO2, 0.10%) in soils over cherty limestone. Zr was most abundant in coarse silts except for two soils over sandstone in which it was most abundant in the very fine sands. Ti increased as particle size decreased. In several soils Ti was present as leucoxene coatings on quartz and chert grains of very fine sand size. This indicates the probable translocation of Ti in soils and its general unsuitability as a stable constituent in soil genesis studies.

On the initial process of horizon differentiation from a uniform parent material

Abstract In a preceding paper (5) the authors proposed a hypothesis that the movement of iron in a soil profile is regulated by the ratio of the amount of the mobilizing agent to the amount of the iron to be mobilized.

On the Horizon Differentiation Process from a Uniform Parent Material

On the Horizon Differentiation Process from a Uniform Parent Material

Fragipan Soils of Illinois: II. Mineralogy in Reference to Parent Material Uniformity of Hosmer Silt Loam

AbstractThe mineralogy of Hosmer silt loam, a bisequal soil with a fragipan, was investigated in order to determine whether there is a lithological discontinuity between the parent material of the upper and lower sequum.Differences observed between the two sequa in respect to the mineralogy of the heavy and light, silt‐size fractions may be accounted for by a progressive decrease in the weathering intensity with depth and are not suggestive of a lithological discontinuity in parent material. The clay mineralogy for the B horizons of the two sequa was similar for the &lt; 0.2µ and the 0.2µ to 2.0µ fractions, taken individually. However, for the total clay fraction, a higher percent of montmorillonite was found in the B′2 horizon of the lower sequum; this may be explained on the basis of illuviation.