Soil Material Classes

Soil classification is really about answering the question what makes a soil? Or, perhaps, what makes one soil different from another? To answer questions like these, soil classifiers create taxonomic rules to separate one kind of soil from another and categorise and make sense of the diverse pattern of the soil continuum. Traditionally a great deal of consideration has been given to characterising and classifying the whole soil profile in a top-down fashion. Pedometric methods allow us to answer the same questions in a bottom-up trajectory. Thus, the starting point is not the whole soil profile or even its major constituents, the soil horizons. Rather we start by classifying the actual, tangible, skeleton of soil itself: the soil material.