The Walker Lane belt is perhaps the eastern periphery of the North American-Pacific plate boundary shear zone, of which the San Andreas is the most prominent feature. The belt accommodates right-lateral shear, but there also extension aligned roughly northeast-southwest. This extension gives rise to the ‘normal’ (extensional) faults that form the eastern margin of the Sierra Nevada (snow covered rocks in the lower left), and also to active magmatic cones (the dark brown conical features in the center bottom) that are cut and right-laterally offset by the Owens Valley fault.