GEA – Grupo de Edafología Ambiental
Departamento de Agroquímica y Medio Ambiente. Universidad Miguel Hernández, Elche, Alicante, Spain
Teaching in geoscience currently is easier than decades ago. Lots of tools can support the lectures in the classrooms, such as innovative teaching web pages, portfolios, social networks pages, etc. All of this can help teachers to do explain geodynamic processes. Pictures with short descriptions are very useful for teaching. An example for soil science is this one, this set of four pictures of different soil profiles that won the European Journal of Soil Science Photocompetition 2011 (figure 1).
All of soil profiles of the figure 1 are located in the Alicante Province (.SE Spain), and all of them are developed over similar lithology: calcareous rocks (limestone). The main difference between them is the age, and therefore the colour. In Alicante Province there are a high diversity of soils because the high variability of all soil forming factors. Among the changes in soil properties during the soil forming processes, one of them is the soil colour.
The first picture corresponds to a Typic Xerorthent (Soil Survey Staff, 2006), a young soil with very low degree of horizon differentiation (Figure 2).
In the figure 3 it can be observed a soil profile more developed with a petrocalcic B horizon. Petrocalcic horizons are formed when secondary calcium carbonate or other carbonates accumulate in the subsoil to the extent that the soil becomes cemented. In this case the soil is classified as a Petrocalcic Calcixerept.
The third picture (figure 4), is of a soil located in the north face of a mountain area (Sierra de Aitana), it is a well developed and preserved soil, and a mollic A, and a calcic B horizon can be well identified. In this case the soil is classified as Typic Calcixeroll. The calcium carbonate accumulated may be well identified in this case because the white colour.
Last picture (figure 5) is a terra rossa soil profile. Terra rossa is a reddish clayey to silty-clay material, which covers limestones or dolomites in the form of a discontinuous layer ranging in thickness from a few centimetres to several metres. In Mediterranean areas, terra rossa are very old soils rich in clay content, and with very low carbonates content despite the fact of be developed over limestone. The red colour is due to the iron oxides accumulated from the long-term weathering of the parent material, and the pedogenic processes. In this case the soil is classified as a Lithic Rhodoxeralf.
- More pictures of soils: http://jorgemataix.carbonmade.com/projects/47854#1
- Pictures of geomorphology: http://jorgemataix.carbonmade.com/projects/47834#1
Soil Survey Staff, 2006. Keys to Soil Taxonomy. 10th ed. NRCS, Washington, DC.