Biozones, stratigraphic log correlation, and corresponding interpretation of paleoenvironments

Stuart Sutherland and Francis Jones
Department of Earth and Ocean Sciences, University of British Columbia
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This exercise is a guided opportunity for any number of students (even hundreds) to start using recently learned, lower-level knowledge about stratigraphy and biostratigraphy in an integrative, interpretation exercise.

Students work in ad-hoc groups of 3 or 4, and the instructor uses clicker questions and short mini-lectures for guidance and pacing. Paper worksheets (one per group) provide both the data students use and spaces for short answer or sketch-based work. The activity targets 3rd or 4th year science (but not necessarily geoscience) students in a large lecture theater.

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This activity could be used in a wide variety of settings. However, it was originally developed for a course called "Earth and Life through Time". Students are required to have 3rd or 4th year standing in a Bachelor of Science degree, but there are no other pre-requisites for the course. Geoscience Majors students are NOT permitted to take the course.

Skills and concepts that students must have mastered

Before beginning the activity, students must have learned basic stratigraphic principles including Walther's law, and the use and meaning of stratigraphic logs. They must also be familiar with very first principles regarding fossil ranges and biochronology.

How the activity is situated in the course

The pre-requisite skills and concepts identified above are covered during the first three weeks of this thirteen week course. In our case, the activity is done on the third Friday of the course, and occupies a full 50 minutes period. There are roughly 150 students who work in self-assigned groups of 4-6 (pairs and solos are not permitted). This group behavior is "standard practice" for every Friday of the course. The instructor guides and paces the work using clicker questions and occasional mini-lectures (less than 5 minutes each), and two teaching assistants are brought in so there are roughly 50 students for each supporting instructor/TA.


Content/concepts goals for this activity

  1. Construct biozones from a given set of fossil ranges.
  2. Correlate given stratigraphic logs using sedimentary facies and fossils.
  3. Interpret, then sketch a cross section of the paleoenvironment at one geological horizon based on the set of stratigraphic logs.
  4. Identify criteria for choosing appropriate fossils for either (a) identifying when a particular paleoenvironment occurred at any location (from a log), or (b) identifying a specific relative time zone in logs at different locations.

Higher order thinking skills goals for this activity

The higher order thinking goal is to begin integrating recently learned, low-level knowledge about stratigraphy and biochronology into a geologic synthesis about temporal and spatial variations of depositional environments.

Other skills goals for this activity

Group work (groups of 4-6 are expected)

Description of the activity/assignment

The 50-minute group-based activity for hundreds of students starts by constructing bio-zones for a given set of fossil ranges. Results are reviewed using a sequence of clicker questions to discuss the optimal biostratigraphic decisions, the necessary types of thinking, and how to articulate a concise yet complete textual description of corresponding biozones.

A set of stratigraphic logs is then used to interpret changes in depositional environment across space and time. Students also decide (and justify decisions) on the optimal choice of fossils for use when interpreting variations in depositional environment. The final result is an interpreted geologic section based on stratigraphic and biostratigraphic data.

This interpretive exercise is only three weeks into a first course on Earth and life through time, so guidance is provided using carefully designed question sequences posed using "clicker" (personal response system) and/or for individual or whole class discussion.

Determining whether students have met the goals

Because clickers are used to help guide the activity, their results serve as immediate feedback both to students and instructors. Completed worksheets are also handed in, common successes and difficulties are determined by teaching assistants, and corresponding feedback is provided to students in the subsequent lesson. A completed version of the worksheet is provided online after in-class feedback discussions. Clicker results and worksheet effort contribute to each student's participation credit, which is accumulated during normal classes and activity classes throughout the term. Students also know that some exam questions will look like those used in worksheet activities.

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