ABSTRACT
Many other soils will remain to be studied. However, the poorly differentiated young-looking soils, for example, Regosols, Leptosols, Fluvisols or even Umbrisols, raise fewer questions on genesis and are, therefore, conceptually less interesting than the rest. This means that we could comprehend the broad lines of their evolution without devoting specific chapters to them. For Cryosols of the Arctic regions, many aspects remain to be discovered, so that the time has not come, at least for the author of this book, to present their genesis. The Chernozem can also give rise to a simplified presentation. Also, the Americans have not deigned to individualize it in their Soil Taxonomy. But it is a well-known soil and most classifications make reference to it. In Europe, it is the fourth soil group by area (Ibáñez et al. 2009). Furthermore, it will enable us to revisit climatic zonality of soils, which is at the core of pedogenesis and by which we have begun as well as we will end this book, before a few words in conclusion.
