On soils with low-to-moderate base saturation and poorly or moderately decomposable litter, the rate of litter decomposition and bioturbation decreases, and a subtype F Mull transient to Moder develops. An Of horizon rich in fine humus (Ohf) forms above the mineral soil surface, which is significantly thicker than the overlying Olf horizon. The A horizon is mostly <8 cm thick. The distinct features of a Moder-like F Mull are:
- Ol horizon and Olf horizon are present;
- Ohf is present, thickness of Ohf >> than Olf horizon; and
- Au or Ah horizon present.