WHAT IS GEOLOGY?
Geology is the study of the Earth. Etymologically, that's literally what is means. The first part, "geo-" is derived from "Gaea", the name of an ancient fake goddess of the Earth. The second part is derived from the ancient word "logia" meaning "writing about" or "study of".
Geology is not just the study of rocks, despite the widespread perception that geology is the study of rocks. Geology is the study of the Earth - the whole Earth. What does the Earth include?
Geosphere - the solid Earth (= rocky portion of the Earth - crust + mantle + core, although some portions of those are liquid or somewhat soft).
Atmosphere - the gaseous layer of Earth occurring above the crust. Earth's air includes ~78% molecular nitrogen (N2), ~21% molecular oxygen (O2), ~0.9% argon (Ar), plus scores of trace gases.
Hydrosphere - liquid water occurring in Earth's ocean basins, in rivers/streams/lakes/ponds, and as groundwater.
Cryosphere - glacial ice, principally occurring on Antarctica, Greenland, and at the tops of some mountain ranges.
Biosphere - the study of Earth's life forms is part of geology; biology is part of geology (although biologists won't readily admit this!).
Pedosphere - an understanding of Earth's soils ("dirt") is part of geology.
Magnetosphere - Earth has a magnetic field, generated by currents in the molten, outer portion of Earth's metallic iron-rich core.
Geology involves a thorough understanding of the
entire Earth. Many researchers refer to
the inter-relatedness of all the "-spheres" listed above as the Earth
system. As such, some geologists have
changed the name for "the study of the Earth" from geology to Earth
system science. There are several other
synonyms for geology, including "geological science",
"geoscience", and "Earth science". All of these terms are synonymous, and as
such, I would suggest that the oldest and simplest term is the only correct
term. GEOLOGY.
Unfortunately, the definition of geology as "study of the Earth" is arbitrarily limiting. Many scientists do planetary geology, which is the study of the geology of the various planets and moons in the solar system.
There are numerous specialties in geology - it's probably the broadest field in all of science. Geology students and professional geologists have dozens and dozens of possible fields to be interested in. A not-complete list is given below.
Aquatic geochemistry - study of the natural and pollution chemistries of water
Archaeological geology - study of the geology of archaeological sites
Atmospheric chemistry - study of the natural and pollution chemistries of air
Atmospheric physics - study of the physics of weather and other atmospheric phenomena
Atmospheric science - study of Earth's (or another planet's) atmosphere
Basin analysis - study of the origin and history of sedimentary basins (depositional centers)
Biogeochemistry - study of the interrelationship between life forms and natural chemical cycles
Biostratigraphy - study of layered rocks based on fossil content
Brachiopodology - study of modern and/or fossil brachiopods
Bryozoology - study of modern and/or fossil bryozoans
Chronostratigraphy - study of the absolute ages of layered rocks
Climatology - study of climate
Coal geology - study of the origin, composition, and occurrence of coal beds
Conodontology - study of conodonts (= phosphatic microfossils that were grasping spines in the mouths of an extinct group of chordates)
Coral paleoclimatology - study of ancient climates using information from fossil corals
Crinoidology - study of crinoids (= sea lilies - relatives of starfish)
Crystallography - study of crystals
Dinosaurology - study of dinosaurs
Earth science - study of the Earth
Economic geology - study of all Earth materials that have value in society
Engineering geology - study of & recognition of & accounting for site-specific and regional geology before, during, and after construction projects (buildings, roads, bridges, geothermal well fields at Ohio State University-Columbus campus, etc.)
Environmental geology - study of the relationship between geology and natural hazards or environmental concerns/problems
Environmental geophysics - study of near-surface geology using geophysical methods at the surface
Exploration geophysics - study of subsurface geology using geophysical methods at the surface to discover petroleum fields, ore deposits, etc.
Field geology - field gathering of geologic information and mapping of geologic units and structures
Forensic geology - study of solving crimes using geologic evidence
Genetic stratigraphy - study of the origin and age of discrete packages of layered rocks unconformably separated from other rock packages
Geoarchaeology - study of the geology of archaeological sites
Geochemistry - study of the chemical composition of & chemical reactions occurring in geologic systems
Geochronology - study of the absolute ages of rocks and geologic events
Geodesy - study of Earth measurements, tides, gravitational field, and upper geospheric movements
Geodetics - study of Earth measurements, tides, gravitational field, and upper geospheric movements
Geodynamics - study of the physics of plate tectonics, structural deformation, and glacial ice sheet formation & retreat
Geographic information systems - analysis and graphical representation of data tied to various geographic locations
Geoinformatics - study of the nature and graphical representation of geologic information tied to various geographic locations
Geological science - study of the Earth
Geology - study of the Earth
Geomathematics - study of the Earth using math
Geometallurgy - study of the geology and mineralogy behind variation in extraction styles of metals from ores during processing
Geomicrobiology - study of the relationship between micro-organisms and various geologic/geochemical phenomena; includes the study of extremophile microbes
Geomorphology - study of the morphology and origin of landforms
Geophysics - study of the physics of the Earth
Geoscience - study of the Earth
Geoscience education - study of how geology is taught in schools
Geostatistics - study of the use of statistics in solving geologic problems
Glacial geology - study of glaciers, their effects, and their deposits
Glaciology - study of glaciers
Gravimetry - study of the strength of and variations in Earth's gravitation field
Historical geology - study of the changes in the geosphere, atmosphere, hydrosphere, cryosphere, pedosphere, magnetosphere, and biosphere throughout the 4.55 billion years of Earth's history
History of geology - study of early geologic ideas and early geologists
Hydrogeology - study of surface water and groundwater
Hydrogeophysics - study of groundwater using geophysical methods at the surface
Ichnology - study of traces made by organisms
Igneous petrology - study of the origin, mineralogy, and chemistry of igneous rocks
Inorganic geochemistry - study of the non-carbon based chemistry of geologic systems
Invertebrate paleontology - study of fossil invertebrates (animals without a backbone)
Isotope biogeochemistry - study of the interrelationship between life forms and natural chemical cycles using isotopic information
Isotope geochemistry - study of the nature and origin of isotopic variations in geologic systems
Isotope geology - study of the nature and origin of isotopic variations in geologic systems
Isotope stratigraphy - study of vertical changes in the isotopic compositions of layered rocks
Limnogeology - study of inland bodies of water (ponds, lakes)
Limnology - study of inland bodies of water (ponds, lakes)
Lithostratigraphy - study of layered rocks based on rock type
Magnetometry - study of the strength and variation of Earth's magnetic field
Magnetostratigraphy - study of layered rocks based on their magnetic properties
Marine geology - study of the oceans
Medical geology - study of the relationship between geology and human health
Metamorphic geology - study of metamorphic rocks
Meteoritics - study of meteorites
Meteorology - study of weather
Micropaleontology - study of microfossils
Mineralogy - study of minerals
Mineral physics - study of the physical properties of minerals
Neotectonics - study of the geology and physics of modern and geologically recent (= post-Oligocene) plate tectonic processes and structural deformation
Oceanography - study of the oceans
Organic geochemistry - study of the carbon-based chemistry of geologic systems
Paleoanthropology - study of fossil hominids
Paleobiology - study of ancient life
Paleobotany - study of fossil plants
Paleoceanography - study of ancient oceans
Paleoclimatology - study of ancient climates
Paleoecology - study of the relationship between ancient organisms and their environment
Paleogeography - study of the geographic changes of continents and ocean basins through geologic time
Paleohydrogeology - study of ancient aquifers and ancient surface waters
Paleohydrology - study of ancient aquifers and ancient surface waters
Paleoichnology - study of traces left by ancient organisms
Paleomagnetics - study of the magnetic properties of rocks
Paleomagnetism - study of the magnetic properties of rocks
Paleontology - study of fossils
Paleooology - study of fossil eggs
Paleopedology - study of ancient soils (paleosols)
Paleoseismology - study of ancient earthquakes
Paleotectonics - study of the geology and physics of geologically ancient (= pre-Miocene) plate tectonic processes and structural deformation
Paleozoology - study of ancient animals
Pedology - study of soils
Petroleum geology - study of oil and natural gas
Petrology - study of the origin, mineralogy, and chemistry of all rock types
Phylogeny - study of the evolutionary relationships among modern and/or ancient organisms
Planetary geology - study of the geology of other planets, moons, asteroids, meteoroids, and comets
Precambrian geology - study of extremely ancient (older than 544 million years) geologic objects, events, and phenomena
Quaternary geology - study of modern and geologically recent (post-Pliocene) geologic objects, events, and phenomena
Reflection seismology - study of subsurface geology using information obtained from artificial, surface-originated shock waves that get reflected back to the surface from rock layers, faults, and other geologic contacts
Remote sensing - study of surficial geology using information obtained from a distance
Rheology - study of the flow physics of rocks, minerals, ice, magma, and water
Scolecodontology - study of scolecodonts (= microfossils of polychaete worm jaws)
Sedimentary geology - study of sediments, sedimentation, and sedimentary rocks
Sedimentary petrology - study of the origin, physical characteristics, and mineralogy of sedimentary rocks
Sedimentology - study of sediments and sedimentation
Seismology - study of earthquakes
Seismotectonics - study of the relationships among earthquakes, fault lines, and plate tectonics
Sequence stratigraphy - study of the subdivision of layered rock successions into discrete, genetically-related, unconformity-bounded packages
Soil science - study of soils
Speleology - study of caves
Stratigraphy - study of layered rocks
Stromatolitology - study of stromatolites (= large, layered structures built up by photosynthetic bacterial mats)
Structural geology - study of the geometry and origin of deformed rocks
Taxonomy - study of naming and classifying modern and/or ancient organisms
Tectonics - study of plate tectonics
Tectonophysics - study of the physics of plate tectonics
Trilobitology - study of fossil trilobites
Vertebrate paleontology - study of fossil vertebrates (animals with a backbone)
Volcanology - study of volcanoes