Leeds page and cation:The fossils change shape, and the changes depend on the oriientation of the fossils. The yellow and blue fossils keep their symmetry, the others including the green one become distorted or sheared. The lines on the green fossil which were at right angles are now oblique. The circle becomes an ellipse. We distinguish two sorts of strain, which are defined in the folowing frames.

This kind of fossil population can be used to determine the finite strain using Wellman's method.