In a previous paper, it was hypothesized based on laboratory experiments, that in north-Idaho loess-influenced soils, freezing may force halloysite colloids to aggregate into sand-sized, stable, particles that resemble weathered micaceous minerals (Clays and Clay Minerals, 39:642-650). In montane meadow soils of the northern sierra Nevada range, similar aggregates comprise a large proportion of the sand-sized fraction. These platy particles are reddish brown in color, have a high Fe content, and are biaxial negative with a small 2V. Similar particles were formed by freezing collodial kaolinite which was extracted from the soil. Microscopic examination of thin sections cut from 0 horizons of the meadow showed particle formation occurred in voids and roots channels, and in some cases could be confused with alluvial argillans. Formation of these stable particles likely influence soil strength, water transmittance, and water retentive properties.

Robert R. Blank
USDA-Agricultural Research Service
Conservation Biology of Rangelands Unit
920 Valley Road
Reno, NV  89512
Tel:  702-784-6057
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