Joint faces commonly show certain structural features such as plumelike markings and fringe joints. The description and classification of these and other peripheral or subordinate structures is useful in providing a material aid to their recognition, and is thus a necessary prerequisite to any discussion of the genesis of joints. The first detailed description and classification was presented by J.B. Woodworth in 1896. More recent study of these structures has provided additional information and makes it desirable to extend and modify this classification. The revised classification recognizes significant subdivisions of the term "joint" and treats additional structural features not discussed by Woodworth or shown in his classification. It is obvious from a consideration of the morphology of joint surface structures that any transcurrent movement along the joint face at the time of generation of the fracture cannot occur without destroying or greatly modifying the surface structure.