Before deformation, planar particles such as micas are randomly distributed. On a stereonet the distribution of their poles is homogeneous. As deformation proceeds the particles rotate so their poles tend to align with the direction of maximum shortening λ3. One can demonstrate that the orientation of planar elements after deformation is a simple function of their initial orientation and of the axial ratios (λ1/λ2; λ2/λ3; λ1/λ3) of the Finite Strain Ellipsoid.
Homogeneous
Strain
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A similar rotation affects linear elements which tend to become parallel to the direction of maximum lengthening (λ1).
Textural analysis consists in plotting on a stereonet the pole of planar elements and linear elements. Their distribution is related to the shape of the FSE and the intensity of the anisotropy is related to the intensity of the strain.
