“En echelon” refers to a pattern of geological features, such as faults, folds, or veins, that are arranged in a staggered or overlapping configuration. This pattern is often indicative of shear stress and is important in structural geology for understanding the deformation of the Earth’s crust and the orientation of stress fields.
Reference: Cowan, D. S. (1999). “Structural Styles in Mylonitic Rocks of the Mecca Hills, Southern California.” Journal of Structural Geology, 21(9), 1285-1302.