What is the defining feature of Inceptisols soils?

Inceptisols are characterized by their weakly developed horizons. This means that they exhibit some level of soil development, but not to the extent seen in more mature soil orders like Mollisols or Alfisols. The defining feature of Inceptisols is their mineralogical composition and the presence of an ochric or umbric epipedon, which indicates a relatively young age and limited profile development. These soils can be found in various climates and landscapes, reflecting recent geological processes and a wide range of environmental conditions.

The other choices represent features that are associated with different soil types. For instance, the low cation exchange capacity rich in iron and aluminum pertains more to some laterite soils or Ultisols, while the thick and dark surface horizon with high base saturation is a trait of Mollisols. Sandy soils with a thick spodic layer are indicative of Spodosols, commonly found under coniferous forests, which have a distinctly different developmental profile compared to Inceptisols.