Module 1: Overview

1.3 Why is Petrology Useful?

Elizabeth A. Johnson; Juhong Christie Liu; and Mark Peale

Applications to Geology

Petrology aids our understanding of the larger Earth system in many ways.  The interactive diagram below shows four examples of how petrology can help us understand questions in other sub-disciplines:

Guided Inquiry

Figure 1.3.1. Geologic applications of petrology.  Click on the information buttons in each diagram to learn more.


Career Paths in Petrology

In academia, petrology can lead to a number of different graduate school options.  These can include projects in volcanology, plate tectonics, experimental petrology of the deep Earth, even the study of meteorites and planetary science.

Students who excel in a petrology course or might do an undergraduate research project in petrology can go on to careers which apply some of the chemistry or materials science skills learned.  These could include: environmental consulting jobs applying hydrology and groundwater geochemistry, working for energy resource companies to site pipelines or model natural gas and petroleum flow through rock units, materials development and testing of solids (glass and concrete/building materials).

Skills that Transfer to Other Careers

Don’t plan on becoming a professional petrologist or someone who teaches about rocks?  No problem – petrology is still important for your career.  Geochemistry and thermodynamics are applied to many Earth systems including hydrology, water geochemistry, and climate systems.  The higher-order thinking skills you learn from a petrology course should be applicable to many situations in your career, no matter what you might end up doing.  Creating hypotheses is important for any scientific field!  Any technical skill you might learn while using instrumentation is valuable, including microscopes, thin section making equipment, an SEM or XRF , or other equipment that might be available at your university.  Finally: the ability to correctly identify rocks is always a valuable skill!

Key Takeaways

Based on the information above, list at least one way petrology can help you in your educational path or future career.  If you are completely unsure of your future path, then describe one aspect of petrology that you think is interesting or would be useful to you in a geosciences career.


Structural Geology:Mikenorton. Asymmetric folds developed within a dextral sense shear zone near Cala Portixol, Cap de Creus area, Catalunya. Wavelength varies with quartz mylonite layer thickness. Pen for scale – 14 cm long. (ret. 7/2/2019) CC BY-SA 3.0

Unported.Ore Deposits:Alexgiovi. Ascending hydrothermal solutions rich in gold, sulfur and metals were channelled upward along major fracture and fault zones. Fluid that made it to the surface would have vented as hot springs and geysers. Localized erosion through the thrust sheet has created windows into the underlying ore-bearing rocks. Adapted from Edwards and Atkinson (1985). (ret. 7/2/2019) CC BY-SA 4.0.

Plate Tectonics:USGS. Map of East Africa showing some of the historically active volcanoes(red triangles) and the Afar Triangle (shaded, center) — a so-called triple junction (or triple point), where three plates are pulling away from one another: the Arabian Plate, and the two parts of the African Plate (the Nubian and the Somali) splitting along the East African Rift Zone. The red triangles show historically active volcanoes. (ret. 7/2/2019) Public Domain.

Geophysics: Oilfieldvegetarian. Simplified and interpreted P- and S-wave velocity variations in the mantle across southern North America showing the subducted Farallon Plate. Adapted from Grand et al. (1997) GSA Today 7(4):1–7. CC BY-SA 4.0.

Wikipedia. Structural Geology. (ret. 7/2/2019)

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1.3 Why is Petrology Useful? Copyright © by Elizabeth A. Johnson; Juhong Christie Liu; and Mark Peale is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

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