Eocene volcanic rocks spanning the North Anatolian Fault Zone in north central Turkey have a common reversed polarity and appear to record a short term volcanic episode useful for identifying subsequent tectonic rotations. Although regional differences are present, no distributed clockwise rotations caused by dextral motion across the fault zone since mid-Miocene times are found. Instead variable anticlockwise block rotations demonstrate that this fault system does not obey theoretical models for crustal behaviour