PHYSICAL, CHEMICAL, AND MINERALOGICAL CHARACTERISTICS OF SOILS FROM VOLCANIC ASH IN NORTHERN IDAHO .1. MORPHOLOGY AND GENESIS

Mission soils, coarse-silty, mixed, frigin Andic Fragiochrepts, are representative of volcanic ash soils found extensively in northern Idaho, northeastern Washington, and northwestern Montana. The B2ir or cambic horizons hve developed from volcanic ash and the underlying IIA' & B' and IIB'2x horizons have fragipans developed in glacial outwash sediments. Horizons from volcanic ash have higher values of estimated allophane, organic C, extractable Fe, Al and Mn, exchangeable H, 1/3- and 15-bar moisture, and CEC than do underlying horizons. Diagnostic properties make the cambic gradational to a spodic horizon.-from Authors