The clearest example of the intimate relationship between the nature of the soil parent material and the properties that the soil eventually acquires through the mediation of soil processes is to be found in soils derived from recent volcanic material. This relationship has been especially well illustrated by a comprehensive review of the topic by Dahlgren et al. (2004). This review highlights the fact that volcanic soils possess distinctive physical, chemical and mineralogical characteristics that are usually not found in soils developed upon other parent materials. Many of these characteristics depend on the ease with which volcanic material is weathered to form poorly crystalline clay minerals, such as allophane, imogolite, ferrihydrite, etc. Other examples illustrating the influence of parent material on soil properties could also be cited. Thus, soils derived from carbonate rock may have such distinctive chemical properties that they are described as specific soil types (Rendzinas) in some soil classifications. Again, soils derived from smectitic-rich parent materials may be classed as Vertisols. In addition, it is widely recognized that parent material may be responsible for the origin of some unusual chemical soil properties, such as the high exchangeable Mg/exchangeable Ca ratio or heavy metal content of serpentinite-derived soils, or for the development of particular soil horizons which are used as diagnostic indices in soil taxonomies.

Notwithstanding these examples, however, parent material per se cannot be said to be a major criterion for soil classification.