Search for Our Past

Christina Belanger,
South Dakota School of Mines and Technology


"Search for Our Past" is an introductory Earth history course. The first third of the course focuses on methods of exploring Earth history through discussions of hypothesis testing and paper-based geology exercises intended provide a foundation for understanding the basis for our current understanding of Earth history. The second two thirds of the course is a walk through time with an emphasis on alternative hypotheses and interpretations using both text book and primarily literature sources.

Course Type: Intro Level:Historical Geology
Course Size:

Course Format:
Lecture only

Institution Type:
Two Year College

Course Context:

The class is approximately 20-30 students with the majority of students taking the course as a required part of the Geology B.S. program; only ~10-15% of students are outside the major. All students are science majors because the institution only offers science and engineering programs and most have previously taken physical geology. Students range from freshman to seniors, but the course is intended for sophomore geology majors.

In your department, do majors and non-majors take separate introductory courses?

If students take a non-majors course, and then decide to become a major, do they have to go back and take an additional introductory course?

Course Content:

"Search for Our Past" covers methods used in exploring Earth history including observational hypothesis testing, absolute and relative dating, stratigraphic interpretation, geochemical, lithological, and faunal proxies for environmental interpretation, reconstruction of continental positions as well as conceptual foundations in Earth climate controls and biological evolution. Students are then exposed to major climatic, tectonic, and biologic events from the Haden to projections of the future. Students are asked to consider multiple hypothesis for the causes underlying the events and to pose different ways of exploring the events using their geological background. Students also write an essay connecting Earth resources used today to the historical processes that led to the development of that resource in a particular location.

Course Goals:

  • Students will know the geological timescale, the placement of major events in Earth history, and key terminology for communicating about Earth history.
  • Students will understand how we obtain information in Earth history and the assumptions underlying the interpretation of that data.
  • Students will be able to interpret the stratigraphic record and evaluate the history of environmental changes from geological records.
  • Students will describe the links between (a) the plate tectonic system, (b) the climate system, and (c) the biosphere through their shared histories.
  • Students will critically evaluate hypotheses about the Earth's past and predictions for the Earth's future, be able to pose their own hypotheses, and suggest methods for testing hypotheses.
What are the main features of the course that help students achieve these goals?
During the portion of the course focusing on methods, students have six paper-based activities that guide them through analyzing and interpreting geologic or biologic data. During the "walk-through-time" students read review articles and primary literature articles about major events in Earth history and are asked to discuss the alternative hypothesis/interpretations offered by the papers during class after having answered questions about the paper for homework. The final assignment asks students to write an essay explaining why a particular earth resource is found in a particular place so that they connect events in Earth history to modern features.


The degree to which students reach the goals in the course is assessed via essay-style long-answer exams. One question on the final is always written to challenge students to identify unanswered questions in earth history, pose two alternative answers to that question, and describe a method of investigation to differentiate those alternative hypotheses. Other questions ask students to relate tectonic events to changes in Earth's life and climate or interpret a stratigraphic column or other geological data.


GEOL323Syllabus2013 (Acrobat (PDF) 95kB Feb24 14)

Teaching Materials:

The Earth Through Time, Levin, 10th ed is highly recommended, but not required. Most students do purchase and use the book.
I selected this text because it gives a fairly even treatment of tectonic, climatic, and biologic events with clear and easy-to-understand maps/figures. It presents alternative explanations and hypotheses for many events and does not "take sides" on critical issues.

References and Notes:

Key Reading Resources:
Other key readings include Annual Reviews articles and other short peer-reviewed journal articles.

Other Supporting Materials:
Geol323 course schedule (Acrobat (PDF) 34kB Feb24 14)