Francisco Ignacio Bongiorno PonzoNorly BelandriaRoberto Úcar2026-03-222026-03-222014http://erevistas.saber.ula.ve/index.php/cienciaeingenieria/article/download/4955/4777https://andeanlibrary.org/handle/123456789/64045This research presents the application of Blake´s method, which is based on the logarithmic spiral equation, to determine the strain ammonites in rocks, whose internal structure is very similar to the graphical representation of the equation. The geodynamic processes acting inside the earth generate strains according to the magnitude of the stress, producing lengthening, shortening and change in the angular structures relationship of these fossil species contained in the rocks, which is studied analytically using this method according to the longitudinal strain, the shear strain and the ratio between the ellipse axes forming strain, taking into account the angle and the internal shear strain. The initial lengths of the Ammonites without deforming, compared with the lengths of deformed ammonites are measured in the field, determining that there are lengths lengthened which coincide with the major axis of the ellipsoid strain and minor principal stress between 0,34 to 7,68 cm, while the values ​​in the shortening direction, coincide with the minor axis of the same ellipse corresponding to the direction of the major principal stress, between 0.04 to 3.94 cm. These directions of the principal stresses coincide with the convergence direction of the Venezuelan Andes.esEllipseGeologyPrincipal axis theoremGeometryPrincipal stressEllipsoidShear stressLogarithmic spiralShear (geology)Geodesyarticle