Sedimentary architecture and genesis of northern Sylt, a Holocene barrier spit located off the German North Sea coast, are presented based on an extensive ground-penetrating radar (GPR) dataset and sediment cores. In parts, the northern spit is underlain by coarse-grained sediments showing at least 10 m thick northeastward dipping foresets. These sediments are interpreted as a precursor spit system which developed during the early Holocene transgression and eventually drowned during continued sea-level rise. The modern spit consists of spit beaches in the central part, a swash-bar sequence facing the open sea, and up to 5 m thick washover fans towards the backbarrier bay. Individual architectural elements, bound by erosional unconformities reflect distinct stages of either spit growth or erosion. The modern spit surface represents a deflation surface, which is bound to the position of the groundwater table. A deflation surface, 1 m below the modern one, is interpreted to be buried during past elevation of the groundwater table, most likely caused by sea-level rise and subsequent creation of terrestrial accommodation space. It is proposed that buried aeolian deflation surfaces are a significant tool in analysing sea-level fluctuations in coastal deposits. New stratigraphic and genetic models for the northern spit of Sylt are presented, documenting that the spit bears a valuable archive of past sea level and climate development.