CREASE FORMATION A crease is a minor fold or localized bending of rock strata, often appearing as a sharp wrinkle or crumple in otherwise continuous layers. Unlike large folds such as anticlines and synclines, creases are smaller, less regular, and often found as surface expressions of deeper tectonic stress. FORMATION PROCESS Crease formations develop mainly due to compressive stress when rocks are pushed together by tectonic plate movement. Instead of breaking, the rock layers bend or wrinkle.