Strain analysis methodologies - Fry method

Identify the centres of all objects and trace these on to paper.

Mark a reference line (e.g. north, or the regional stretching lineation etc.) on to the paper.

Take another piece of tracing paper and mark an orientation to match that on the other sheet.

Also mark a reference point on the paper.

Place the reference point on the tracing paper over one of the marked centres, keeping the two sheets oriented parallel against the same marker.

Trace off the centre points of all the other markers.

Move the reference point onto the next centre and repeat the process, keeping the two sheets oriented parallel against the same marker.

Repeat this procedure for all centres.

The result is a scatter of points but the area around the reference point is vacant with an elliptical shape.

The shape (axial ratio) and orientation (with respect to the reference direction) of this vacant ellipse represents the strain ellipse.

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Last update: 29th January 2002
Copyright © Dr G. Lloyd, School of Earth Sciences, Leeds University, 2002