In structural geology, en échelon veins, "en échelon gash fractures" or "Tiger Stripes" are structures within rock caused by noncoaxial shear.
En echelon veins can be parallel or subparallel, closely-spaced, overlapping or step-like minor structural features in rock. These step-like features can be faults, or tension fractures, that are oblique to the overall structural trend. They originate as tension fractures that are parallel to the major stress orientation, ÃÂ<sub>1</sub>, in a shear zone. They are subsequently filled by precipitation of a mineral, typically quartz or calcite. As soon as they form, they begin to rotate in the shear zone. Subsequent growth of the fracture therefore causes the vein to take on a shape. They can be used to determine the incremental kinematics of the deformation history of the rock.