Sedimentology has seen many significant advances and changes over the past 40 years, ranging from facies modelling to sequence stratigraphy; chemostratigraphy to basin analysis; and the integration of studies of physical, chemical and, increasingly, biological processes in the interpretation and prediction of sedimentary environments and products. The subject is becoming ever more interdisciplinary and applied, and now has far more links to other physical sciences. Research and debate are continuing afresh as we move into this new interdisciplinary phase and promise many developments and increased uses of our subject. Now seemed a good time to publish a series of review papers concerning some key current areas of research. We hope that these papers will provide comprehensive starting points for those wishing to become acquainted with an area, act as stimuli for debate, and provide awareness and ideas for future research avenues. No issue of this sort can, of course, ever be truly comprehensive in its coverage: these reviews concern only selected snippets from the wide scope of sedimentology and each has, of necessity, been selective in its own area.