Article: An improved method of analysing distortion in fossils

Fossils distorted by tectonic strain can be reconstructed to their original shape if the strength and direction of the principal axes of strain are known. The ratio and orientation of the principal strains can be calculated by measuring the distortion in the angle between the median and transverse line in bilaterally symmetrical fossils like brachiopods and trilobites by several methods:a. They can be determined with exactitude if two such fossils are found on one bedding plane.b. If a number of single fossil specimens is available, but the relative orientations of their median and transverse lines from specimen to specimen are unknown, the amount of deformation can be calculated by Breddin's method, making use of the most strongly deformed former right angle in the collection.c. When the principal strain ratios have been calculated, the orientations of the principal axes of strain can be determined in any single specimen.The different processes are greatly simplified by a special device described in the text.