| 8. coarse-silty, mixed, superactive,
This soil has formed in loess
and has silty textures throughout. Native vegetation consists of
grand fir and ninebark.
The subsoil fragipan (Btxb horizons), with a bulk density
of 1.7 g/cm3, is part of a older, buried soil that began forming ~40,000 years ago. The A, Bw, and part of the E horizons have formed in younger loess. Some volcanic ash is mixed with the loess in the surface horizons.
The fragipan significantly alters local hydrology. Perched zones of saturation form above the fragipan
during winter and persist into late spring. Relatively little water is able to percolate through the fragipan, resulting in considerable lateral throughflow.
here for more information on the Santa series, and click
here for a map of this soil's geographic extent.
(scale is in decimeters)