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
Nature study students, who were influenced by this philosophy, went on to provide the nature study knowledge in public schools. It was Agassiz who coined the phrase, "Study nature, not books." Nature study can be described as "conceiving of the movement as a loose coalition of communities composed of individuals, societies, and institutions able to find some common ground in the study and appreciation of the natural world". In "Leaflet I: What Is Nature-Study?" from a 1904 collection nature study lessons, Liberty Hyde Bailey presented the following description of nature study: NATURE-STUDY, as a process, is seeing the things that one looks