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Abstract Tephra is a unique volcanic product with an unparalleled role in understanding past eruptions, long-term behavior of volcanoes, and the effects of volcanism on climate and the environment. Tephra deposits also provide spatially widespread, high-resolution time-stratigraphic markers across a range of sedimentary settings and thus are used in numerous disciplines (e.g., volcanology, climate science, archaeology). Nonetheless, the study of tephra deposits is challenged by a lack of standardization that inhibits data integration across geographic regions and disciplines. We present comprehensive recommendations for tephra data gathering and reporting that were developed by the tephra science community to guide future investigators and to ensure that sufficient data are gathered for interoperability. Recommendations include standardized field and laboratory data collection, reporting and correlation guidance. These are organized as tabulated lists of key metadata with their definition and purpose. They are system independent and usable for template, tool, and database development. This standardized framework promotes consistent documentation and archiving, fosters interdisciplinary communication, and improves effectiveness of data sharing among diverse communities of researchers. 

Abstract. Volcanic fallout in polar ice sheets provides important opportunities to date and correlate ice-core records as well as to investigate theenvironmental impacts of eruptions. Only the geochemical characterization of volcanic ash (tephra) embedded in the ice strata can confirm the sourceof the eruption, however, and is a requisite if historical eruption ages are to be used as valid chronological checks on annual ice layercounting. Here we report the investigation of ash particles in a Greenland ice core that are associated with a volcanic sulfuric acid layer previouslyattributed to the 79 CE eruption of Vesuvius. Major and trace element composition of the particles indicates that the tephra does not derive fromVesuvius but most likely originates from an unidentified eruption in the Aleutian arc. Using ash dispersal modeling, we find that only an eruptionlarge enough to include stratospheric injection is likely to account for the sizable (24–85 µm) ash particles observed in the Greenlandice at this time. Despite its likely explosivity, this event does not appear to have triggered significant climate perturbations, unlike some otherlarge extratropical eruptions. In light of a recent re-evaluation of the Greenland ice-core chronologies, our findings further challenge the previousassignation of this volcanic event to 79 CE. We highlight the need for the revised Common Era ice-core chronology to be formally accepted by the widerice-core and climate modeling communities in order to ensure robust age linkages to precisely dated historical and paleoclimate proxy records. 

Abstract Efforts to date the oldest modern human fossils in eastern Africa, from Omo-Kibish^1–3and Herto^4,5in Ethiopia, have drawn on a variety of chronometric evidence, including⁴⁰Ar/³⁹Ar ages of stratigraphically associated tuffs. The ages that are generally reported for these fossils are around 197 thousand years (kyr) for the Kibish Omo I^3,6,7, and around 160–155 kyr for the Herto hominins^5,8. However, the stratigraphic relationships and tephra correlations that underpin these estimates have been challenged^6,8. Here we report geochemical analyses that link the Kamoya’s Hominid Site (KHS) Tuff⁹, which conclusively overlies the member of the Omo-Kibish Formation that contains Omo I, with a major explosive eruption of Shala volcano in the Main Ethiopian Rift. By dating the proximal deposits of this eruption, we obtain a new minimum age for the Omo fossils of 233 ± 22 kyr. Contrary to previous arguments^6,8, we also show that the KHS Tuff does not correlate with another widespread tephra layer, the Waidedo Vitric Tuff, and therefore cannot anchor a minimum age for the Herto fossils. Shifting the age of the oldest knownHomo sapiensfossils in eastern Africa to before around 200 thousand years ago is consistent with independent evidence for greater antiquity of the modern human lineage¹⁰.