Sedimentary records of reversals for the past 12 million years exhibit preferred longitudes of their VGP paths. This observation may be related to long term aspects of core-mantle dynamics. However, it has been suggested that sedimentary VGP paths could be an artefact due to smoothing which mixes non antipodal pre- and post-transitional directions. We show here that smoothing over unrealistically long time scales is required to generate intermediate directions of magnetization which are purely mixtures of pre- and post-transitionals directions in sediments whose remanence is primarily depositional (DRM) or post-depositional remanence (PDRM). Sedimentary records of transitions showing VGP paths confined to the planes of immediately pre- and post-transitional VGPs have however been observed. These can be explained by non-axisymmetric bias in the non-reversing field [Gubbins and Bloxham, 1987; Constable, 1992>, which plays a role in reversals. Therefore, provided that magnetization directions are properly cleaned to give single component directions, the preferential longitudes of reversal VGP paths will be due to field behaviour and not to an artefact of the magnetization process. If, however, mixtures of primary magnetization acquired at the time of the formation of the rock and secondary magnetization acquired later are measured, then artefacts will be generated. ¿ American Geophysical Union 1992