Abstract: An E-W striking,subvertical shear zone in the granodiorite of Lake Edison,Central Sierra Nevada,California,U. S. A. was studied to determine the variation in deformation microstructures with distance from the shear zone center. Field and thin-onsecti relations demonstrate that the shear zone nucleated on a pre-existing quartz-filled fracture. Selective chemical etching was used to reveal dynamically recrystallized grain-boundaries of quartz in the granodiorite,offset aplite dike and deformed fracture-filling. The recrystllized grain-size of quartz decreased with increasing shear strain toward the center of the shear zone. This would suggest significant variation in the apparent magnitude of tectonic stress. Important effects of strain on the microstructures are suggested by our observations. This phenomenon is contrary to that usually reported in experimental studies,which found no dependence of recrystallized grain size on strain.