Upper Palaeolithic layers and Campanian Ignimbrite/Y-5 tephra in Toplitsa cave, Northern Bulgaria

This paper reports the preliminary results of two test pit excavations in Toplitsa cave in Northern Bulgaria and discusses the potential for future investigations of the Pleistocene layers associated with Marine Isotope Stage 3 and the transitional Middle to Upper Palaeolithic period. We describe the lithostratigraphic layers, archaeological finds and features attributable to the Upper Palaeolithic. The preliminary chrono-cultural interpretation of the early Upper Palaeolithic geoarchaeological deposit at Toplitsa cave is based on the identification of Campanian Ignimbrite/Y-5 (CI) tephra, radiocarbon dates and the technological assessment of a small lithic artefact assemblage in comparison with the regional Initial Upper Palaeolithic (IUP) technologies. Toplitsa cave, located in the Eastern Balkans (Northern Bulgaria), was excavated in 2011 with the main goal of investigating deposits encompassing the transition from the Middle to Upper Palaeolithic. Two test pits (TP) were excavated: TP I, incorporating four lithostratigraphic layers, was located in the cave interior and TP II, encompassing six lithostratigraphic layers, was established closer to the cave entrance. Both TPs were generally poor in archaeological remains which impacted the chrono-cultural attribution of the Pleistocene layers. Moreover, in some spots Holocene faunal remains likely intruded into older layers. In consequence, the preliminary chronological investigation has been focused on applying both tephrochronology and radiocarbon dating of the early Upper Palaeolithic deposits. We present a preliminary assessment of the stratigraphy and report on the identification of large amounts of glass shards belonging to the CI eruption (ca. 39,000 years old (ka BP)) in TP II Layers 2 and 3, below which there is a well preserved hearth. This fire-pit carved in Layer 5 (TP II) and underlying the Y-5 tephra is the most significant find. Two Ursus spelaeus teeth from the underlying Layer 5 have been radiocarbon dated to 49,770–45,750 calibrated years before present (cal BP; 95.4% probability) and to 48,210–45,050 cal BP (95.4% probability). The lithics found in Layer 5 are technologically consistent with the Initial Upper Palaeolithic (IUP) or possibly with other transitional Middle to Upper Palaeolithic assemblages. Layer 5 from TP II in Toplitsa overlaps chronologically with other regional records. These include the final Middle Palaeolithic with leaf points from Musselievo (estimated to ca. 50–45 ka cal BP), the transitional Middle to Upper Palaeolithic assemblage from Temnata Cave Layer VI (trench II, which is covered by CI tephra and has been dated to older than 39 ka BP), the earliest laminar Upper Palaeolithic (i.e. IUP) from Temnata Cave Layer 4 (trench I, dating from 47.6 to 40.5 ka cal BP), the IUP from Bacho Kiro Cave Layers J and I (dating to 46.0–43.3 ka cal BP) and Kozarnika cave Layer 6/7 (dated to ca. 49.1–44.0 ka cal BP).