Four cores from southwestern Sweden are presented together with their tephra geochemistry. Two cryptotephra horizons were confirmed geochemically in the cores, the Vedde Ash and the Hässeldalen Tephra. The Lateglacial Hässeldalen Tephra (11 360–11 300 cal. a BP) offers great potential as a regional isochrone to add a new degree of certainty to the deglaciation chronology of southern Sweden, including the extent of glacial Lake Bolmen. In addition, the geographical distribution of the Hässeldalen Tephra has recently been extended outside of Sweden, making it an important time-marker horizon in northern Europe. There are potential difficulties, however. Proper identification of the actual isochrone is complicated by the vertical pattern of shard distribution, which could be the result of several eruptive events, as well as by the fact that shards from the 10-ka Askja horizon (10 500–10 350 cal. a BP) were found in close stratigraphical proximity. The geochemical data presented are the result of improved EPMA methodology, which significantly reduces sodium mobilization. The results therefore have slightly altered values, which has consequences for classifying new finds when they are compared with previous data for geochemically similar tephras. Finally, potential indications of the Borrobol/Penifiler horizon are presented, although the existence of the horizon could not be confirmed geochemically. This highlights the need to retrieve cores from different locations within a basin based on an analysis of basin morphology if horizons are to be located.

New results are presented from the Borrobol type-site, northern Scotland, as well as from the two Swedish sites, Hässeldala port and Skallahult, where a Borrobol-like horizon has previously been found. New major element geochemistry data is reported reflecting improved EPMA (Electron Probe Micro-analysis) methodologies. These newer methodologies slightly alter the geochemistry which should be considered when making comparisons between sites. Trace element data is also presented for the Borrobol-like horizons found in Sweden and the Borrobol site. Initial findings indicate that there is no difference between the trace element geochemistry of the Swedish sites and the Scottish Borrobol horizon