Clay mineral distribution in the Hiawatha sandy soils of Northern Wisconsin

Mineralogical analyses were made of the day, silt, and sand fractions of the Podzols Hiawatha loamy sand and Hiawatha sand. The layer silicates how chemical weathering as a function of depth in both soils. A high charge dioctahedral montmorillonite was dom-inant in all fractions (-5g) of the-'/2 horizon and its origin was attributed to weathering of an interstratified vermiculite-chlorite similar to that in the B2 horizon. The 2 to 0.2/z fraction of the Hiawatha loamy sand B2 horizon contains 14 percent chlorite and 18 per-cent vermiculite with no montmorillonite, and the Hiawatha loamy sand.42 horizon con-tains 33 percent montmorillonite with little interstratified chlorite-vermiculite. Quartz also showed a soil depth function in the fine silt. It is higher in amount in the,42 than the Bz horizon, attributable to its relative stability in the Podzo1-42. Below the Bz it drops markedly in amount, attributable toa difference in silt deposition. The similarity of ratios of resistant heavy minerals (greater than 2.95 sp. gr.) in differ-ent horizons indicates uniform origin of the sand fractions of these soils. Light mineral contents in the sand fractions for all analyzed horizons are also similar. However, particle size data indicate silt and possible clay addition to both the//2 and//2 horizons. Depth functions in these soils are developed to a marked extent, apparently owing to (1) low amount of fine fraction originally present for weathering, (2) greater amount of water cycled through the 212 than the B2 horizon, (3) rapid and frequent cycling of avail-able water owing to coarse texture, and possibly (4) effects of podzolization. The Omega, Ahmeek, and Iron River soils of northern Wisconsin also showed a similar though not so marked tendency to accumulate montmorillonite in the z12 horizon