Lithology
Lithology (from the Greek λίθος, lithos, stone; and λόγος, logos, study) is the part of geology that studies the characteristics of the rocks that appear constituting a certain geological formation, it is say a lithostratigraphic unit, on the surface of the territory, or also the characterization of the rocks of a specific sample. It is distinguished from petrology, which studies and describes (petrography) in all its aspects what characterizes the various types of rocks that exist, although in Spanish and French lithology was formerly used as a synonym for petrology.. For example, the study of the characteristics of granites, or the specific type of granites found in a certain region, is to do petrology; the study of the various rocks (which may include granites) that a road under construction must cross, as part of a geotechnical study, is lithology.
It helps to understand the concept of lithology the existence of specifically lithological maps, which are maps that represent the distribution of surface rocks, those that outcrop (in the air) or are covered only by regolith, soil and vegetation, or products of human activity, such as buildings or roads.
When one type of rock, or the systematic alternation of several, cover an extensive surface, the evolution of the relief is conditioned. Lithological geomorphology is the study of relief from the point of view of the influence of the type of outcrop rock. Significant examples of relief types due to lithological causes are karstic relief or badlands; In both cases, climatic or structural conditions are also required. Volcanic reliefs are also very characteristic, but in this case it is more due to structures, such as volcanic cones, which are explained by their formation process, than by a special behavior of volcanic rocks in the face of the factors that shape the relief.
Although etymologically the word lithology is the name of a science, equivalent to the word petrology, in its modern use it is a metonymy, for which it is used to designate what science has described, that is, the outcropping rocks of a place. For example, we can see written "the lithology of the eastern Vera and Sorbas depression..." to describe the type of rocks that emerge in the relief of that region.