Magnetometer Survey
Initial Publication Date: July 5, 2007
Summary
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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Context
Audience
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
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.
Goals
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
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.