When writing a paper using GSA style, exact quotes may be used but they must be properly cited within the text using quotation marks, and must include the author's last name, the year of publication and the page number where the quote is from.
Quotations and paraphrasing may be indicated in one of two ways with this style:
1. Begin the sentence with the author's last name followed by the date of publication in parentheses. If the information is being paraphrased that is sufficient. If the information includes a direct quote, at the end of the quote include the page number(s) in parentheses.
According to Thuna (2016), the earth is very old.
According to Thuna (2016), "the earth has been around for 4.543 billion years." (p. 205).
When an in-text citation has more than one author, here are some guidelines:
Two authors: Include the last names of both authors.
Three to five authors: Include the last names of all the authors the first time you cite the paper. If you cite the paper again, list only the last name of the first author followed by et. al.
Six or more authors: For all citations, use only the last name of the first author followed by et. al.
Arias, 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, no. 12, p. 61–74.
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, doi:10.1016/j.epsl.2004.12.013.
Author(s) Last Name(s), Initial(s)., Year of publication, Article Title: Journal Title, Volume number, Page numbers. doi (if available).
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.
Author(s) Last Name(s), Initial(s)., Year of publication, Book Title:Place of publication, Publisher, Number of pages.
Book Chapter/Paper in multi-author volume
Shipboard Scientific Party, 1987, Site 612, in Poag, C.W., Watts, A.B., et al., Initial Reports of the Deep Sea Drilling Project, Volume 95: Washington, D.C., U.S. Government Printing Office, p. 31–153. Taylor, J.C.M., 1990, Upper Permian—Zechstein, in Glennie, K.W., ed., Introduction to the Petroleum Geology of the North Sea (third edition): Oxford, UK, Blackwell, p. 153–190.
Author(s) Last Name(s), Initial(s)., Year of publication, Chapter name, in Editor name, ed., Book title: Place of publication, Publisher, Number of pages.
Willingham, C.R., Rietman, J.D., Heck, R.G., and Lettis, W.R., 2013, Characterization of the Hosgri Fault Zone and adjacent structures in the offshore Santa Maria Basin, south-central California: Chapter CC of Evolution of Sedimentary Basins/Onshore Oil and Gas Investigations–Santa Maria Province: U.S. Geological Survey Bulletin 1995-CC, 105 p., http://pubs.usgs.gov/bul/1995/cc/pdf/bul1995cc.pdf.
Author(s) Last Name(s), Initial(s)., Year of publication, Report Title: Publisher, Volume (if applicable), Number of pages, url if available.