Clay mineralogy and chemistry of soils formed in volcanic materials in the xeric moisture regime of northern California

The clay mineralogy and chemistry were determined for five pedons derived from tephra and volcaniclastic materials in northern California. These soils are believed to have formed under vegetation and climatic conditions similar to those at present; coniferous vegetation and a xeric soil moisture regime with approximately 1000 mm of annual precipitation. The five pedons showed a surface enrichment of organic carbon (3.6–6.7%), an acidic to...