Understanding Geologic Maps

Cara Burberry

University of Nebraska-Lincoln

This is used in the 300 level structural geology course - a required course for undergraduates wishing a geology degree.

Students must recall concepts such as the Law of Superposition, Law of Cross-Cutting Relationships, relationship of outcrop patterns to topography and the concepts of anticlines, synclines, thrust faults and normal faults. All of these are introduced in the 100 level course that is a prerequisite to this class, but the lectures in Weeks 2 & 3 recapitulate on these concepts.

This is the second part of a sequence of map exercises - first set in Week 3 of class. Part 1 involves some time on Google Earth and an example map deconstruction and geologic history given by the instructor. Later exercises (fieldwork, synthesis report and exam) also involve some elements of map interpretation so it is important for the students to have plenty of time to master these concepts.

Geologic map interpretation, using ALL the information on the map, recalling concepts learned in earlier courses.

Higher order skills - to be able to take individual elements of the map (structural elements, lithologic elements, interaction with topography) and combine these into a coherent geologic history of an area. By providing a series of targeted questions and starting by deconstructing the map, students are later able to write geologic histories of other map areas without this level of instruction.

Writing a coherent and technically sound, simple geologic history of the area.

This is an exercise in which students are reintroduced to geologic maps and encouraged to "deconstruct" the map into constituent elements in order to understand the geologic history of the area. The preceding lectures in the course have recapitulated material that the students have covered in Introduction to Physical Geology. During class, the students work through the maps that were part of lab exercises in the Intro level course, so that basic concepts are recalled (superposition, cross-cutting relationships, basic faults and folds). The final product is a geologic history of this map area.

Evaluation - is the geologic history produced a complete and coherent (bullet points are acceptable) history of the segment of map they are looking at?

Later in the course - can the student take the same thought pattern and apply this to another map area? Field area? Exam question?