Genesis of Lamellae in Sandy Soils of the Northern Highland in Wisconsin

Abstract

Lamellae are characterized as a soil horizon or band that is less than 7.5 cm thick that contain an accumulation of oriented silicate clay bridging sand and silt grains. Formation of lamellae differ from region to region. Multiple hypotheses and theories of lamellae formation have been formulated to explain this phenomenon. Potential factors are climate, parent material, and sources of clay. Sandy soils in the Northern Highland of Wisconsin are relatively young soils formed in depositions from the last glacial period. The sand deposits of the Northern Highland are in a continental climate influenced by Lake Superior. These northern Wisconsin lamellae indicate physical and chemical differences compared to those in older soils of the driftless, unglaciated area of southwestern Wisconsin. Lamellae formations, particularly in sandy regions, are morphologic anomalies that are not well understood. For this reason, further investigation was done to test hypotheses of lamellae formation. The texture (optical investigation), mineralogy (by XRD), and overall composition of select sandy soils of the Northern Highland of Wisconsin were examined to determine the genesis mechanism of lamellae within these soils. It was determined that the formation of lamellae bands at four different locations was pedogenic (versus depositional) based on the clay mineralogy and sand content.