Petrology Petrology Petrology (from the Greek πέτρος, "pétros", "rock" and λόγος, "lógos", "subject matter", see -logy) is the branch of geology that studies rocks and the conditions under which they form. Petrology has three subdivisions: igneous, metamorphic, and sedimentary petrology. Igneous and metamorphic petrology are commonly taught together because they both contain heavy use of chemistry, chemical methods, and phase diagrams. Sedimentary petrology is, on the other hand, commonly taught together with stratigraphy because it deals with the processes that form sedimentary rock. Lithology was once approximately synonymous with petrography, but in current usage, lithology focuses on macroscopic hand-sample or outcrop-scale
What Is the Third Estate? and operated by independent associations, and therefore society would be self-governed. A comprehensive collection of writings on the topic was released under "Pluralist Theory of the State". Modern equivalent theories building upon the ideas within pluralistic state theory are libertarian socialism and free-market anarchism. An example of the former is guild socialism, one of the founders of which is G. D. H. Cole mentioned above. What Is the Third Estate? What Is the Third Estate? () is a political pamphlet written in January 1789, shortly before the outbreak of the French Revolution, by the French thinker and clergyman Abbé Emmanuel