Teach the Earth > Geophysics > Teaching Activities > Magnetometer Survey

Magnetometer Survey

Michael John Harris
James Madison University
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This activity has benefited from input from faculty educators beyond the author through a review and suggestion process. This review took place as a part of a faculty professional development workshop where groups of faculty reviewed each others' activities and offered feedback and ideas for improvements. To learn more about the process On the Cutting Edge uses for activity review, see http://serc.carleton.edu/NAGTWorkshops/review.html.

This page first made public: Jul 5, 2007


This activity collects two sets of magnetic data, using two different types of magnetometers, one which collects individual data points, and one that collects continuous readings. Both methods have pros and cons, in data collection efficiency, real-time interpretations, data analysis, and data interpretation, and this exercise stresses these situations. These are then used as examples for other geophysical methods and instruments as they are introduced.

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This assignment is used in a senior year elective Introduction to Geophysics course, which stresses field methods of shallow instruments and environmental problems.
Designed for a geophysics course

Skills and concepts that students must have mastered

  • use of magnetometers
  • field work preparations
  • use of spreadsheets

How the activity is situated in the course

This exercise is one of several exercises that allow the students to prepare and run their own field project.


Content/concepts goals for this activity

  • understanding the operating procedures of field magnetometers
  • understanding what creates magnetic anomalies and how magnetometers can aid in differentiating anomalies from background readings (interpretation skills)

Higher order thinking skills goals for this activity

  • planning an appropriate data collection procedure
  • evaluating real-time field data for potential alterations to collection procedure
  • analysis of data; spreadsheets versus black-box software

Other skills goals for this activity

  • oral communication; if enough students are available, groups are made and each does one type of magnetometer data collection, then each group presents their data and their interpretations, followed by overall discussion of the instruments, collection strategies and the geologic interpretations

Description of the activity/assignment

The week previous to this exercise, the students are taught how to use an individual collecting point proton-precession magnetometer and a Cs-vapour automated magnetometer. Once they are comfortable with the instruments they are shown a plot of land over which they will design their own data collection strategy for an unknown anomaly. The day of the exercise, the students are placed into groups (no more than four per group), and assigned one of the two types of magnetometers. Each group then has up to 90 minutes to agree to a data collection strategy, collect their data, and make initial interpretations of their data. The proton precession magnetometer group needs to enter their data into a spreadsheet to normalize the data to note anomolies, or onto a map and contour their values. The Cs-vapour magnetometer group needs to download their data onto a laptop (or desktop), and use the interpretation software for their 2D and 3D maps. Presentations of data, interpretations, and discussion follow this.
Uses online and/or real-time data
Uses geophysics to solve problems in other fields
Addresses student misconceptions

Determining whether students have met the goals

This first attempt of this exercise just used subjective evaluations, based on participation, ability to use the instrument, to understand the data that was being observed, and the attempts made to interpret the data. Some of the data (or similar magnetic data) is used on the practical parts of mid-term and final exams.

More information about assessment tools and techniques.

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