A1 Refereed original research article in a scientific journal
A new, ~4500‐year varve record and high‐resolution tephrochronology from lake Hämälänlampi, eastern Finland, provides age constraints for the Furnas C and the Glen Garry/Askja A‐2000 eruptions; 
Authors: Kalliokoski, Maarit; Erola, Veera; Saarni, Saija
Publisher: Wiley
Publication year: 2026
Journal: Journal of Quaternary Science
ISSN: 0267-8179
eISSN: 1099-1417
DOI: https://doi.org/10.1002/jqs.70079
Publication's open availability at the time of reporting: Open Access
Publication channel's open availability : Partially Open Access publication channel
Web address : https://doi.org/10.1002/jqs.70079
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/524882665
Self-archived copy's licence: CC BY
Self-archived copy's version: Publisher`s PDF
The northern European distal cryptotephra framework is constantly developing both in terms of identification of new tephra horizons and improved age constraints for the already well-established tephra marker horizons. However, many prehistoric tephra layers have only been dated by the radiocarbon method, with its inherent problems. Here, we present a new similar to 4500-year, continuously varved lacustrine sediment record and tephrochronology from lake Hamalanlampi, eastern Finland. The varve chronology was established by repeated varve counts from epoxy-impregnated sediment blocks and selected elemental maps (Si, K, Fe and Mn) produced by micro-XRF scanning. The sediment core was investigated for the presence of cryptotephra, and the exact location of the nine identified cryptotephra horizons was pinpointed with either 0.5- or 1-cm depth resolution. The volcanic glass shards were geochemically characterised and correlated to their source eruptions. As a result, we report the first findings of the Hekla 1947, Furnas C and Hekla C tephras in Finnish environmental records, and provide varve ages for the Furnas C, Hekla Y, Hekla C and Oraefajokull 3.5 ka tephras for the first time. We also suggest a new, high-resolution varve age 128-117 BCE for the Glen Garry tephra, based on integration of varve ages from several studies. (c) 2026 The Author(s). Journal of Quaternary Science Published by John Wiley & Sons Ltd.
Keywords:
Finnish tephrochronology, Furnas C tephra, Hekla tephra, Oraefajokull 3.5 ka tephra, varve chronology
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Funding information in the publication:
We thank Timo Saarinen for his help in the early stages of this research project and Tapio Suominen for assistance in lake coring. We acknowledge financial support from the Academy of Finland (grant no. 339789) and Maa- ja vesitekniikan tuki ry. Open-access publishing was facilitated by Turun yliopisto, as part of the Wiley-FinELib agreement. Open access publishing facilitated by Turun yliopisto, as part of the Wiley - FinELib agreement.