The Johntom series consists of shallow, well drained soils formed in colluvium and residuum from rhyodacite and quartz latite, with a component of loess and volcanic ash. These soils are on mountain ridges, shoulders, and upper backslopes. Slopes are 8 to 65 percent. These soils are usually moist but are dry in all parts of the moisture control section for 75 to 90 consecutive days following the summer solstice. Depth to a lithic contact ranges from 10 to 20 inches.
Reaction is neutral or slightly acid throughout.
The C horizon has chroma of 2 or 3 dry or moist. It is very gravelly sandy loam, extremely gravelly sandy loam, or extremely gravelly coarse sandy loam. It is 40 to 70 percent pebbles and 5 to 20 percent cobbles. These are the Aldax , Bakeoven , Bodacious , Bodell , Couleedam , Lickskillet , Limekiln , Plaskett , Rockly , and Venator series. Aldax soils are dry in all parts of the moisture control section for more than 90 consecutive days following the summer solstice and have a mollic epipedon that extends to the lithic contact.