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Geology 303A: GSA Style

GSA Style

The Geological Society of America (GSA) Style Guide is often used by Geoscience students to format their manuscripts, in-text citations, and reference lists. The Geological Society of America publishes journals whose articles are in GSA style (e.g., one journal is named, Geology), so do take a look inside these journals for examples of in-text citations within the text and a reference list at the end of the articles.

In-text citation is the brief form of the citations appearing in the body of the work.
Reference list is the complete form of the citations appearing at the end of the work.

In-Text Citation Examples

In-Text TIPS

ONE or TWO authors

  • include author(s) last names and year of publication if available
  • with one author, use last name and year
  • with two authors, use 'and' between authors' last names 

Jones (2021) has discovered that ...

Smith and Peters (2019) have suggested that ...

It has been confirmed that the mineral will cool out of the liquid state (Smith and Peters 2019; Lee, 2020; Stevens, 2021).

THREE to FIVE authors

  • include author(s) last names and year of publication if available
  • with three to five authors, use the last name of the authors first time its cited, and then if you want to cite the document again, just use the first author followed by et al. (stands for 'and others')

Experimental evidence suggests that all mineral fibres are capable of causing fibrosis (Smith, Lee, and Jones, 1999).

Many researchers in academia and industries are interested in reducing particle sizes from few sub-micrometers to nano-meter levels (Smith et al., 1999).

SIX OR MORE authors

  • with six authors or more author, always use the name of the first author followed by et al.

A spectroscopic study confirmed the presence of the  mineral paceite (Wilson et al., 2008).

Jones et al. (2020) attributed the peak to ...

Stevens et al. (2013), Milne et al. (2015), and Wang et al. (2019) agreed that the formation of ...

Citing Quotes

Usually scientists avoid using direct quotes and prefer to summarize ideas and facts from a source. However, if you choose to use direct quotes,

  1. Place quotation marks within the quote
  2. Include page number(s) if present

Evans (1997) has stated that "Nickel ferrite nanoparticles have several possible applications as cathode materials" (p. 11).

It has been stated that "Nickel ferrite nanoparticles have several possible applications as cathode materials" (Evans, 1997, p.11).

GSA Style - Sources for EXAMPLES


GSA LibGuide (UofSC)  |  GSA LibGuide (Bennington College)

Reference List Tips

Reference TIPS

  1. Title the reference list as REFERENCES CITED.
  2. The reference list is arranged in alphabetical order by authors’ last names.
  3. Initials are always used for first and middle names (i.e., authors' first and middle names are never spelled out in the GSA style).
  4. For references with more than 10 authors, shorten the author list to the first author's name plus “et al.” 
  5. The journal titles are not italicized or underlined.
  6. Second and all subsequent lines are always indented.
  7. If you know a paper’s DOI number (DOI is a Digital Object Identifier) for a document, include it.
  8. For website citations, include the month and year the site was accessed in parentheses at the end of the reference.
  9. References mentioned in the text, figures, captions, tables, and appendixes must be listed in the References Cited section.
  10. Do not cite papers that are unpublished, in preparation, submitted, in review, or in revision.

e.g., for a journal article
Author(s), Year of publication, Article title: Journal name, volume number, page numbers, doi.

Reference List Examples


Balco, G., Stone, J.O., and Mason, J.A., 2005, Numerical ages for Plio-Pleistocene glacial sediment sequences by 26Al/10Be dating of quartz in buried paleosols: Earth and Planetary Science Letters, v. 232, p. 179–191,

Brias, O., and Denyer, P., 1991, Estructura geológica de la región comprendida en las hojas topográficas Abras, Caraigres, Candelaria y Río Grande, Costa Rica: Revista Geológica de América Central, v. 12, p. 61–74.

Brown, J.R., Beroza, G.C., Ide, S., Ohta, K., and Shelly, D.R., 2009, Deep low-frequency earthquakes in tremor localize to the plate interface in multiple subduction zones: Geophysical Research Letters, v. 36, L19306,

Bureau of Land Management, 2010, Plan amendment/final EIS for the Genesis Solar Energy Project, Vol 1: (accessed March 2014).

Johnson, A.B., 2001, Raw data for relay stations AB1–AB15 in the Mojave Desert: (accessed December 2001).

Smith, D.C., Fox, C., Craig, B., and Bridges, A.E., 1989, A contribution to the earthquake history of Maine, in Anderson, W.A., and Borns, H.W., Jr., eds., Neotectonics of Maine: Maine Geological Survey Bulletin 40, p. 139–148.