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 Art? Aylmer Maude, translator of many of Tolstoy's writings, calls it "probably the most masterly of all Tolstoy's works", citing the difficulty of the subject matter and its clarity. For a comprehensive review of the reception at the time of publication, see Maude 1901"b". Bayley, John (1986 [1966]). ""What is Art?" - excerpt from Tolstoy and the Novel" in Bloom, Harold (ed.). Leo Tolstoy. New York: Chelsea House. p. 141-152. Jahn, Gary R. (1975). "The aesthetic theory of Leo Tolstoy's "What is Art?"". "Journal of Aesthetics and Art Criticism" 34 (1): 59-65. Maude, Aylmer (1901a). “"What is Art?" - An Introduction”,