An abrupt global climate change event in Earth history- Evidence from the ocean
Skills and concepts that students must have mastered
Conceptual understanding of the carbonate system in the ocean (i.e. the CCD and the factors that influence it). Understanding of at least some of the possible factors that influence C isotopic values in marine carbonates. Experience working with and logging marine sediment cores and understanding of the kinds of materials that characterize the sea floor.
How the activity is situated in the course
Content/concepts goals for this activity
- Accurate (well-supported) interpretation of core log information and marine geochemical data.
Higher order thinking skills goals for this activity
- Synthesizing multiple forms of paleoceaongraphic data to make a well-supported interpretation of changing conditions in the climate system.
- Interpreting both temporal and spatial variability in oceanographic conditions at the Walvis Ridge core sites.
Other skills goals for this activity
- Building skill and comfort using GeoMapApp, Adobe Photoshop, and Illustrator to produce a technical poster.
Description and Teaching Materials
This activity requires that students have access to computers with internet access and software for graphing, and image, data, and poster editing (I prefer Adobe, but others are certainly possible). All materials needed to carry out the exercise are given and briefly described below:
- Student handout for PETM project assignment (Microsoft Word 2007 (.docx) 34kB Jun11 14) The handout includes a description of the project, along with the goals, tasks, ODP data to be accessed, and information on assessment.
- I ask students to use GeoMapApp (geomapapp.org), a nice earth science freeware product which they have previously worked with, to make the required maps for their posters and as a portal to the ODP Leg 208 core imagery and logs. Data for Leg 208 can also be directly accessed here: iodp.tamu.edu/janusweb/general/dbtable.cgi?leg=208&site=1267.
- Geochemical data for PETM project (Excel 2007 (.xlsx) 61kB Jun11 14) Two datasets needed to complete the exercise come from Zachos et al., 2005 paper published in Science on the evidence for major changes in ocean chemistry during the PETM.
- An example student poster (Acrobat (PDF) 1.1MB Jun22 16) (a high resolution poster (Acrobat (PDF) 353.8MB Jun11 14) is also available).
Teaching Notes and Tips
- I have given my students 2.5 weeks to work on this project, including two 3-hour laboratory sessions where I was available for aid and consultation. This amount of time seemed to work well.
- I instruct my students explicitly to NOT dig into the peer-reviewed literature on ODP Leg 208 for others' intepretation of the data and the event. Instead, I make sure that they understand that I am looking for their own data-supported interpretation.
- A major challenge in this exercise is producing a figure with neatly aligned core imagery and geochemical data for the five coring sites. To get students off on the right foot, I first drew a rough sketch of what this figure should look like for their reference. Regardless, the mechanics of aligning the data are tedious and take some time.
- Students come into my course with varying levels of experience using Adobe Photoshop and Illustrator software. Plan on providing aid to students in some simple functions such as cropping and rotating core images, bringing files into Illustrator and working with layers. One could also have students make their posters using more user-friendly software (i.e. Powerpoint).
References and Resources
Zachos, J. C., U. Röhl, S. A.Schellenberg, A. Sluijs, D. A. Hodell, D. C. Kelly, E. Thomas, M. Nicolo, I. Raffi, L. J. Lourens, H. McCarren, D. Kroon, 2005, Rapid Acidification of the Ocean During the Paleocene-Eocene Thermal Maximum. Science, v.308, p.1611-1615.