A Study of the Origin and Distribution of Loess in Southern Indiana

Abstract

AbstractSoil profile studies were made along two traverses extending from the Wabash River in a southeasterly direction across southern Indiana for the purpose of determining the distribution of loess in this area. The variation in thickness of the loess mantle with distance from the Wabash River, the assumed source, was measured, and equations of the curves showing the relationship were calculated. X‐ray diffraction studies were made of the medium and fine silt fractions of the A2 horizon of 10 profiles along the southern traverse. The ratio of the quartz/feldspar intensities was determined using sodium fluoride as an internal standard. The calcium, sodium, and potassium content of the medium silt fractions of these 10 horizons was determined by flame photometry. The equation for the curve fitted to points plotted along the northern traverse was Y = 122 − 47 log X, where Y is the depth of the loess in inches and X is the distance from the Wabash River in miles. The equation for the southern traverse was Y = 125 − 53 log X. The X‐ray diffraction studies indicate that the quartz/feldspar ratio may be used as an index of weathering. The correlation coefficients for the relationship between the quartz/feldspar ratio and distance from the Wabash River were 0.95 and 0.96 for the medium and fine silts, respectively. The results of the chemical determinations substantiated the findings of the X‐ray diffraction studies. It is concluded that loess was transported across southern Indiana for a distance of about 90 miles.