What Is Geology?

What is geology? What do geologists do? How to Become an Geologist?

What Is Geology?

Geology is an earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time. Geology can also refer generally to the study of the solid features of any terrestrial planet (such as the geology of the Moon or Mars).

Geology gives insight into the history of the Earth by providing the primary evidence for plate tectonics, the evolutionary history of life, and past climates. Geology is important for mineral and hydrocarbon exploration and exploitation, evaluating water resources, understanding of natural hazards, the remediation of environmental problems, and for providing insights into past climate change. Geology also plays a role in geotechnical engineering and is a major academic discipline.

What do geologists do?

Mapping & Fieldwork

  • Field mapping:Geologists traditionally record in field notebooks their observations, including sketches, measurements (for example, the angle of tilted strata), and narratives. The validity of these observations remains; however, digital photographs now frequently supplement sketches, and instrumentation enhances measurement accuracy (for example, more precise locations are possible with a global positioning system instrument than with simple reference to position in relation to topographic and cultural features). Increasingly, field narratives are written and organized on a notebook computer or a personal digital assistant (PDA).
  • Sampling: Geological sample preparation is a vital stage in the analytical process, given the highly variable nature of mineral samples. The purpose of sample preparation is the production of homogeneous sub-sample, representative of the material submitted to the laboratory.
  • Geotechnical mapping assesses the engineering properties of a rock and its stability prior to undertaking any sort of construction or modification of the rocks (such as building a tunnel).


Well logging, also known as borehole logging is the practice of making a detailed record (a well log) of the geologic formations penetrated by a borehole. The log may be based either on visual inspection of samples brought to the surface (geological logs) or on physical measurements made by instruments lowered into the hole (geophysical logs). Some types of geophysical well logs can be done during any phase of a well’s history: drilling, completing, producing, or abandoning. Well logging is performed in boreholes drilled for the oil and gas, groundwater, mineral and geothermal exploration, as well as part of environmental and geotechnical studies.

Some types of logging include:

  • Rock core logging (or rock chip logging): Core logging is a highly specialized skill requiring careful observation and accurate recording. Geophysical logging of the hole created in the drilling process is sometimes done without the collection of the core.
  • Mud logging: Mud logging is the creation of a detailed record (well log) of a borehole by examining the cuttings of rock brought to the surface by the circulating drilling medium (most commonly drilling mud).
  • Geotechnical logging: this assesses how strong or weak rocks are below the ground using rock core.

Laboratory Work

Many geologists undertake laboratory work in their careers. A lot of what we know about the geology of the world and other planets has been discovered in laboratories. Researchers and those who work for some geology-related companies work in laboratories. There are also some geoscientists employed specifically in commercial laboratories that a huge number of geology-related companies (e.g. mining, oil & gas, engineering and environmental companies) use to acquire data.

Laboratory work can include:

  • Microscope: work looking at very fine details of rocks and fossils
  • Geochemical analyses: using chemical methods to reveal details about samples (such as their metal content or the quality of oil).
  • Geomechanical tests: testing the strength of rocks.

Computer-based work

All geologists will do a lot of their work on computer, often using specialist software, mostly in offices but field-based computer work is becoming more common. This can include:

  • Geographical Information Systems (GIS) – essentially, this is field mapping on computers – producing a digital database of the field data acquired by geologists.
  • Database management – Geologists spend a lot of time ensuring databases are up to date. This can be vital for the modelling processes described below.
  • Modelling programs – this has become increasingly important for geologists, both those who do research and in commercial companies. This means many geologists are trained in specialist software or programming. Geologists produce and maintain these for a range of purposes:
    * Modelling geological processes (often for research purposes)
    * Producing a 3-D model of a mineral deposit, oil field or aquifer.
    * Modelling the subsurface geology that an engineering project will modify.

Geology as a Career

Earth Science Teachers: teach ‘earth science’ (a mixture of geology, oceanography and climatology) in junior and senior high schools. A teaching certificate from a professional education program is also normally required.

Economic Geologists: explore for and help produce metallic (iron, copper, gold, etc.) and non-metallic (coal, granite dimension stone, limestone aggregate, sand and gravel, etc.) rock and mineral resources of economic value.

Engineering Geologists: investigate the engineering properties of rock, sediment and soil below man-made structures such as roads, bridges, high-rise buildings, dams, airports, etc.

Environmental Geologists: study the environmental affects of pollution on ground and surface waters and surficial materials (rock, sediment and soil), and also recommend solutions to environmental problems. They are also interested in understanding, predicting and mitigating the effects of natural hazards, such as flooding, erosion, landslides, volcanic eruptions, earthquakes, etc.

Geochemists: investigate the chemical composition and properties of earth materials, especially polluted ground and surface waters, fossil fuels (such as petroleum and coal) and other resources of economic value.

Geology Professors: teach geology courses and conduct research in colleges and universities.

Geomorphologists: study the origin and evolution of landscapes on the continental surfaces.

Geophysicists: use the principles of physics to investigate the structure of the Earth’s deep interior, explore for economic resources in the subsurface, and monitor pollution in ground water.

Glacial or Quaternary Geologists: study the history of geologically recent (Quaternary period) glaciers as well as the sediment deposits and landforms they produced.

Hydrogeologists: are concerned with water in the Earth’s subsurface, including its sources, quality, abundance and movement.

Hydrologists: are concerned with water on the Earth’s surface, including its precipitation, evaporation and runoff, and its abundance and quality in streams and lakes.

Marine Geologists: study the physical, chemical and biological characteristics of the sediments deposited on the ocean floors and the rocks that underlie them.

Mineralogists: investigate the origins, properties and uses of the minerals occurring within the Earth’s rocks.

Paleontologists: study the remains of ancient animals and plants (fossils) in order to understand their behaviors, environmental circumstances, and evolutionary history.

Petroleum Geologists: explore for and help produce petroleum and natural gas from sedimentary rocks.

Petrologists: study the origins and characteristics of igneous, metamorphic and sedimentary rocks.

Sedimentologists: investigate the origins and characteristics of sediment deposits and the sedimentary rocks that form from them.

Seismologists: are geophysicists who study earthquakes, both to better understand the physical processes involved and to interpret the deep internal structure of the Earth.

Stratigraphers: investigate the time and space relationships among sedimentary and other rocks on local to global scales, and are also interested in the geochronology (absolute dating by radiometric methods) and fossil content of rock layers.

Structural Geologists: study the folding, fracturing, faulting and other forms of deformation experienced by rocks below the Earth’s surface, and are also interested in how these processes relate to global Plate Tectonics.

Volcanologists: investigate volcanoes, especially their eruptions and deposits, in order to better understand physical processes involved and to predict volcanic eruptions.

What is Geologist Salary?

The American Association of Petroleum Geologists reports every year on average salaries spanning years experience and degree acquired. You will notice that entry-level geologists earn on average $92,000, $104,400, and $117,300 for a bachelor, masters, and PhD degree in geology, respectively.

How to Become an Geologist?

To become a geologist, you need to begin by earning a Bachelor of Science degree in Geology or a closely related field such as Environmental Science. Completing coursework geology, mathematics and physics is a great way to build an educational foundation for your prospective career as a geologist.

Depending on where your career ambitions and interests lie, you will likely need a graduate degree in geology to become a senior level geologist. Employers also usually accept a degree in Environmental Engineering provided the candidate has experience in geology.

Depending on the requirements of the employer, a Master’s degree in Geology or Environmental Science is typically sufficient for many applied research positions. To become a geologist who works in research and university teaching positions a PhD in Geology or Environmental Science is needed.

Geologists must also complete continuing education throughout their careers in order to keep their skills current stay up to date with advancements in the field.