Detailed morphological, lithostratigraphical and biostratigraphical studies in the lower Nith valley and estuary, Scotland, disclose evidence for changing relative sea levels during the Holocene. The Main Postglacial Transgression was in progress in the area around c. 7500 14C years bp (8350 cal. years bp) to c. 7800 14C years bp (c. 8600 cal. years bp), perhaps by c. 7675 14C years bp (c. 8490 cal. years bp); relative sea levels fell briefly after c. 7200 14C years bp (c. 8020 cal. years bp); then resumed their rise after c. 7000 14C years bp (c. 7800 cal. years bp) and culminated by c. 590014C years bp (c. 6720 cal. years bp) reaching the Main Postglacial Shoreline, the evidence for which is widespread in the lower Nith valley. Subsequently, relative sea levels may have fluctuated, modifying or exceeding Main Postglacial Shoreline features along the estuary coastline before falling to a lower shoreline and then falling farther to reach present levels at c. 1760 14C years bp (c. 1800 cal. years bp), after which there is no evidence for relative sea-level change in the area. This sequence is considered broadly comparable with sequences recorded at other sites along the northern shore of the Solway Firth, in particular confirming evidence for a fluctuation in the Main Postglacial Transgression and for the age of the Main Postglacial Shoreline.