Reconstructing the depositional environment of a local rock formation

Katrin Monecke
,
University of Pittsburgh at Johnstown
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Summary

Each group of students works on a well defined local outcrop and decribes sedimentary units and fossil content. Based on this data they reconstruct the depositional environment, put it into a broader paleogeographic context and compare it to a modern environment.

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Context

Audience

Historical Geology, required undergraduate course for geology majors and Earth & Space education majors

Skills and concepts that students must have mastered

  • prerequisite: Physical Geology
  • covered concepts in class prior to project:
    • overview of sedimentary rocks
    • overview of major fossil groups
    • brief introduction to sedimentary structures and interpretation of depositional environments (ideally covered in a lab period)
    • paleogeography and life of time periods represented in outcrops (in this case the Middle and Later Paleozoic)

How the activity is situated in the course

The project combines the knowledge of many earlier labs and lectures such as interpretation of sedimentary environments, Paleozoic fauna and paleogeography. It is the culminating project of this course in which many concepts of historical geology/ paleontology / sedimentology can be applied.

Goals

Content/concepts goals for this activity

Students should learn how to investigate and interpret a sedimentary rock outcrop and its fossil content.

Higher order thinking skills goals for this activity

Students have to apply their classroom and lab knowledge in the field and reconstruct the depositional environment from the rock record. In order to better picture the ancient depositional environment they have to compare it to a modern environment.

Other skills goals for this activity

The project requires some literature search (geologic maps, stratigraphic context, fossil record interpretation). The final report requires good writing and drawing skills and the students have to learn how to work independently in small groups of 2-4 people.

Description of the activity/assignment

Description of the activity/ assignment

Students receive some general data on the regional geology and the rock formation that they are going to study. They also get examples of outcrop sketches and symbols used for the description of sedimentary rocks. Based on the description of the sedimentary units and the fossil content of the outcrop students interpret the depositional environment, compare it to the paleogeography of that time period and compare the ancient environment to a modern one. Each group has to hand in a report and presents the outcrop to their class mates during one of the following lab periods. This project combines multiple concepts of historical geology, sedimentology and paleontology.

Provided materials

(ideally acessible in lab room over the whole duration of the project)

- regional geologic maps

- general stratigraphic column

- images of fossils which can be found in that outcrop

- if availalable, provide a master fossil collection for that formation so that students can compare their fossils

- example of an outcrop sketch

- example of a depositional environment sketch (e.g. a floodplain)

- list of commonly used symbols for sediments/ fossils

Determining whether students have met the goals

The students work will be evaluated based on their report and the outcrop presentation in the field.

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