The Moray Firth is the largest of only three major coastal embayments on the East Coast of Scotland. The relationships between the offshore, coastal margin and fluvial sediments are examined in terms of processes and deposits. These suggest that the large post-glacial accretions of sediment infilling the inner firths are in part attributable to transport of material from the offshore zone. Since the fluvial input to the area appears to be relatively small and much is retained on estuarine tidal flats it is likely that the offshore contribution is the most important constituent of the deposits of the coastal margin. The other major source is glacial and fluvioglacial material now being reworked by marine activity.