A. Constant Bed Thickness perpendicular Fold surface B. Thickness constan A parallel B similar parallel to axial surface C. A common center of curvature D. Planar limbs and sharp angular C concentric D chevron Inge zone Classification of folds based on the fold profileA . Constant Bed Thickness perpendicular to Fold surface B. Thickness constant parallel to axial surface C. A common center of curvature D. Planar limbs and sharp angular hinge zone Classification of folds based on the fold profile