Henneke Series

Henneke Series

One of the unusual parent materials in California is serpentinite. This is an ultrabasic or ultramafic rock. Ultrabasic or ultramafic means that there is no quartz in the rock and that the rock consists of mostly iron and magnesium minerals. This unusual parent material is not only the state rock, it forms unusual soils. Several soil series are found in California formed on serpentinite. This one is dark, clay-rich and shallow to the hard bedrock. It is a Mollisol. Soil scientists believe that the organic matter accumulates in the soil because of the high clay content and because microorganisms are inefficient in their use of organic matter additions due to the high Mg and low Ca in the soil. This particular profile is only 40 cm thick. It is dark throughout and, compared to the overlying and underlying horizons, has a significant increase in clay between the second and third pins.

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