Teaching notes


Audience: undergraduate- or graduate-level petrology course

Skills and concepts that students must have mastered:
  • divergent plate tectonics (mid-ocean ridges)
  • major-element data and variation diagrams
  • fractionation
  • how to use Excel to manipulate data and make x-y plots
  • incompatible and compatible elements

How the activity is situated in the course: This activity can be used as a supplementary exercise to complement lectures on basalts and/or mid-ocean ridges. It may be completed in or out of class.


Content/concepts goals for this activity: Students who complete this exercise should be able to:
  1. use the PETDB database to download a global dataset of glass analyses from mid-ocean ridge basalts
  2. use Excel spreadsheets to plot major-element variation diagrams
  3. recognize and interpret the significance of correlated data on major-element variation diagrams and plots of geochemical composition vs. axial ridge elevation

Higher order thinking skills for this activity: This exercise requires students to formulate hypotheses and to compare/contrast data.

Other skills/goals for this activity: Obtaining and using data from online databases like NAVDAT informs the students about the powerful resources that have recently become available to the scientific community via the creation of digital cyberinformatics and cyberinfrastructure. Carefully guiding students into these databases, through the various steps required to screen, download, import, and use their data, students are empowered to think and act like scientist in tangible and practical ways.


Students are presented with a series of questions to answer during this exercise. It is up to the instructor how the students' data might be evaluated. This exercise might to used to form the basis for an open-ended group discussion.