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
Institute for the Study of Human Knowledge web site for a project entitled "The Human Journey". It aims to "follow humanity from our origins in Eastern Africa and the Middle East to the present day, with an eye to what comes next." Institute for the Study of Human Knowledge The Institute for the Study of Human Knowledge (ISHK) is a non-profit educational charity and publisher established in 1969 by the noted and award-winning psychologist and writer Robert E. Ornstein and based in Los Altos, California, in the USA. Its watchword is "public education: health and human nature information." Robert Ornstein, psychologist, writer and professor at Stanford University,