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 Spiritism? What Is Spiritism? What Is Spiritism? ("Qu'Est-ce Que le Spiritisme" in French) is a brief introduction to Spiritism written by Allan Kardec in 1859, which is about a quarter of the length of The Spirits Book. Modern editions are augmented by a brief biography of the author, written by Henri Sausse, in 1896 which is mostly focused on his role in the History of Spiritism. The book is structured as a series of conferences about Spiritism, intended to quench the public curiosity and dismiss false notions about the doctrine. It is not intended as an initiation and is not seen