Citation Styles for the Sciences

GSA Style is the citation standard created by the Geological Society of America and is commonly used in the field of geology.

A GSA citation consists of two parts:

• In-text citations: Every time you present information that you have obtained from another source, you must create an in-text citation for it. GSA Style does not use footnotes. Avoid using direct quotes and instead summarize in your own words the ideas or facts that come from a source. Summaries need to include in-text citations.
• References Cited: At the end of your literature review, you should have a reference list that will include all the sources that were cited in your paper.
  • The content of citations will vary depending on the source, but the following rules apply to all citations:
    • List references alphabetically by author's surname.
    • List authors by full last name and initials for first and (if applicable) middle names.
  •  If a source's DOI (digital object identifier) is available, you should include it at the end of the citation. (This is only applicable to online sources, not print sources).
  • The first line of each citation should be aligned with the left margin. The second and subsequent lines of each citation should be indented by 0.5 inches to create a hanging indent.

When you present information that comes from another source, you should create an in-text citation that includes both the author's last name and the four digit year of publication. You can do this in one of two ways:

• Mention the author's last name in the sentence where you are presenting their findings, followed by the year in parentheses. 
  • Example: Smith (2011) found evidence that suggests that the Ramapo Fault has the potential to produce a major earthquake.
• At the end of the sentence, include both the author's last name and year of publication, separated by a comma.
  • Example: Evidence suggests that the Ramapo Fault has the potential to produce a major earthquake (Smith, 2011).

• Two authors: Include the last names of both authors either in the sentence or in parentheses.
  • Examples:
    • Brown and Matthews (2015) suggest that the Ramapo Fault will cause a major earthquake.
    • It has been suggested that the Ramapo Fault will cause a major earthquake (Brown and Matthews, 2015).
• Three to five authors: Include the last name of each author the first time the source is cited in your paper. For each in-text citation of the source after that, list only the first author followed by et al.
  • Examples:
    • First citation of source: It has been suggested that the Ramapo Fault will cause a major earthquake (Brown, Matthews, and Smith, 2015).
    • Later citations of same source: It has been suggested that the Ramapo Fault will cause a major earthquake (Brown et al., 2015).
• Six authors or more: For every in-text citation, list the last name of the author followed by et al.
  • Example:
    • It has been suggested that the Ramapo Fault will cause a major earthquake (Barnes et al., 2013).

Abstracts

Author(s), Year of publication, Title, Source, volume (if applicable), Pages.

Example:

Sears, J.W., 2012, Making Nuna and breaking Rodinia: Implications of Siberia-Laurentia connections for supercontinent cycles:

Geological Society of America Abstracts with Programs, v. 44, no. 7, p. 378.

Articles (articles in academic journals, newspapers, magazines)

Author(s), Year of Publication, Title: Subtitle (if applicable): Publication, Volume number, Page numbers, doi (if applicable).

Example:

Coogan, L.A., and Hinton, R.W., 2006, Do the trace element compositions of detrital zircons require Hadean continental crust?:

Geology, v. 34, p. 633–636, doi:10.1130/G22737.1.

Books (books, pamphlets, and multi-volume publications such as encyclopedias)

Author(s), Year of Publication, Title: Place of publication, Publisher, Number of pages.

Example:

Allmendinger, R.W., Cardozo, N., and Fisher, D., 2011, Structural Geology Algorithms: Vectors and Tensors in Structural Geology:

New York, Cambridge University Press, 304 p.

Chapters in a Book or Papers in a Multi-author Volume

Author(s), Year of Publication, Title of chapter, in Author(s)/editor(s) of full volume, Title, Place of publication (if available), Publisher (if available), Volume (if available), Pages.

Example:

Sawyer, D.S., Buffler, R.T., and Pilger, R.H., 1991, The crust under the Gulf of Mexico basin, in Salvador, A., ed.,

The Gulf of Mexico Basin: Boulder, Colorado, Geological Society of America, Geology of North America, v. J, p. 53–72.

Government Publications

Author(s), Year of publication, Title: Publisher, Volume (if applicable), Pages.

Example:

Hay, R.L., 1963, Stratigraphy and zeolitic diagenesis of the John Day Formation of Oregon: University of California Publications in

Geological Sciences, v. 42, p. 199–262.

Maps

Author(s), Year of publication, Title: Publisher, Series number (if available), Scale (if available), Number of sheets (if available), Number of text pages (if applicable).

Example:

Ernst, W.G., 1993, Geology of the Pacheco Pass quadrangle, central California Coast Ranges: Geological Society of America

Map and Chart Series MCH078, scale 1:24 000, 1 sheet, 12 p. text.

Symposiums and Conferences

Author(s), Year, Title, in Title of proceedings, Month and year of conference (include this only if year of conference differs from publication year): Place of publication: Publisher, Pages

Example:

Baar, C., 1972, Creep measured in deep potash mines vs. theoretical predictions, in Proceedings, Canadian Rock Mechanics

Symposium, 7th, Edmonton: Ottawa, Canada Department of Energy, Mines and Resources, p. 23–77.

Websites

Author, Year of publication, Title of webpage: URL (Month and year that site was accessed).

Example:

Scotese, C.R., 2003, PALEOMAP Project: http://www.scotese.com (accessed August 2019).