EXPERIMENTAL DEFORMATION OF VISCOUS LAYERS IN OBLIQUE STRESS FIELDS
Alternating layers of soft viscous wax and asphalt were squeezed in various orientations within a constant-strain squeeze box. Compression produced folds and small wrinkles whose axial orientation is determined solely by the intersection of the plane normal to the direction of maximum shortening with the layer surface. Formation of folds in viscous materials appears to be a function of the strain rate.