Hornblende-quartz rock of the Coniston Shear Zone I (CSZ I) at the Grenville front, Canada, was deformed dominantly by semibrittle flow of hornblende-quartz aggregate and locally by cataclastic flow of hornblende aggregates. Fracturing and slip along fractures produced mesoscopic domino-style deformation. Void formation associated with domino-style deformation was prevented by leveling the corners of the slid segments of individual mesodominoes, producing narrow shear zones. The shear zones eventually coalesced to form the dominant mylonitic C-foliation. On the microscopic scale, semibrittle flow was achieved by dynamic recrystallization of quartz concomitant with microcracking and microfaulting of hornblende into microdominoes, and rotation, shear and separation of the microdominoes. Plastic deformation of quartz accommodated the rotation and shear of the microdominoes, thereby obviating the space problem. Local cataclastic flow occurred in the hornblende domains and produced R 1 Riedel shear surfaces. The observed processes are consistent with greenschist-grade retrograde metamorphism accompanying post-orogenic uplift along this zone.