Figure F27. Composite digital photographs of the E/O boundary during ODP Leg 199 using biostratigraphic (nannofossil and radiolarian) and magnetostratigraphic data. The position of the boundary (at the 33.7-Ma isochron) has been calculated through linear interpolation between paleomagnetic and/or biostratigraphic indications. E/O = Eocene/Oligocene boundary.