Generally speaking, your geology classes will ask you to cite your sources using GSA format - the standard format for your discipline. (Note: Always check with your professor to determine which citation style they prefer for you to use).
For help in properly citing your sources, you can visit: https://library.augustana.edu/friendly.php?s=citation. You can also access this page from the icon on the library's homepage.
You can also find out more information on how to cite in GSA style here:
https://www.geosociety.org//documents/gsa/pubs/GSA_RefGuide_Examples.pdf
There are a number of free citation managers for students to keep track of their citations as they complete research. Below are links to several of the citation managers that work well with OneSearch:
All Three Programs Can: