Measurement of compass orientations of rock fractures

submitted by

Thomas W. Oesleby Northwest College
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This is a partially developed activity description. It is included in the collection because it contains ideas useful for teaching even though it is incomplete.

Students learn to use a geologic compass to measure rock fractures and formulate a hypothesis to explain the origin of the fractures
GSA Poster (PowerPoint 3.4MB Jan12 04)

Learning Goals


Higher Order Thinking Skills:

Interpretation of data; formulation of a hypothesis

Other Skills:

use of a geologic compass


Instructional Level:

6-8 through undergraduate entry, general public

Skills Needed:

Use of a protractor

Role of Activity in a Course:

part of a sequence of laboratory exercises on rocks and field trips

Data, Tools and Logistics

Required Tools:

simple geological compasses

Logistical Challenges:

some students require minor additional instruction using a compass.


Evaluation Goals:

Evaluation Techniques:

Students plot fracture rose diagrams and write a report summarizing procedure, results and a hypothesis


Students are taken on a field trip to a glacial moraine. Students are grouped into pairs, and each pair is given an instruction sheet (which includes a table for recording data) and a geologic compass. Following a brief demonstration on the use of a geologic compass to measure azimuths of vertical and near-vertical fractures on boulders, the student pairs are sent off in different directions with instructions to each measure fracture orientations on 20 boulders (ten per student) and to take about 20 minutes to complete the task. Instructions also request a basic lithologic identification of each boulder studied. As part of their follow-up report, students plot fracture orientations into a rose diagram, and then speculate on the origin or cause of the fractures by formulating a hypothesis.