The abstract ideas, principles, scales and models earth science uses to describe and measure the planet, as distinct from the physical rocks, minerals, places, organisms and people this atlas also holds. Grouped here by the discipline each concept belongs to, live or disclosed: Geology, Seismology, Mineralogy, Climatology, Geochronology, Geophysics, Stratigraphy, Paleoclimatology, Meteorology, Hydrology and Volcanology. Belongs here: a named principle, law, scale, model or theory, whether currently accepted, historical, or still debated. Does not belong here: a discrete physical process or event, held under Processes or Phenomena instead, or a person, held under Scientists, even where that person's name is attached to the concept, such as the Richter Magnitude Scale naming Charles Richter.